Details: Bilibili and Bullet Comments

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After we published our Bilibili report, many people reached out to learn more about the bullet comments and why they are unique to just Bilibili. On the surface, it may seem that this is a feature that is easy to copy or nothing more than a trivial spin on the traditional below the video comments. However, as we will explore below, the lovability of the bullet comments is not specific to the product’s implementation, but rather as an enduring reminder that you are not alone and there is a whole world that shares your interest. In this follow up, we expand on bullet comments through three lenses: functionality, culture, and community.



  • Viewers have the ability to toggle bullet comments on or off and can adjust viewing preferences like comment speed, size, color, font, and transparency. They can also restrict comments to show only from users with certain levels.
  • “Anti-block” feature ensures that a certain percentage of the screen remain unblocked, utilizing Bili-developed AI that identifies the subjects within a video and directs the comments to pass “behind” those subjects when flying across the screen.

Data advantage.

A user can click to show Bili’s timestamped log of bullet comments on the right (see image below; can be sorted by time posted or time in video), which not only allows users to reread comments they may have missed, but more significantly, it gives Bilibili a data advantage. The content of the comment combined with knowing the exact moment the user wants to express it, allows Bili to understand viewer sentiment and what resonates most with viewers, which can be used to influence their inhouse OGV content production. Furthermore, similar to hashtags, they can also be used to automatically tag content and generate summaries to entice and recommend to viewers.

Comment with context.

If you look through the comment section on any YouTube video, you’ll see things like “0:58 AMAZING”. These comments are an attempt to add context to the users comments and “react” to a specific portion of the video. “0:58 AMAZING” is a poor workaround to the Bilibili method as it’s annoying to rewind the video to see what the commenter is referring to. Swipe right to see how Bili’s comment system compare to YouTube’s comment system.

Bullet Comments Change Viewing Experience.

On each video’s viewing page, under the video, viewers are able to see the amount of “current viewers” and “current bullet comments”. For the screenshot shown below, there are ~14,000 total bullet comments, but only 1,593 “current” bullet comments. That means that when watching this video, we were only shown 1,593 of the ~14,000 comments – typically the most recent X number of comments. While some videos are overflowed with bullet comments, this is a way of preventing a complete screen blockout. On that note, each individual bullet comment is also constrained to 40 Chinese characters (if you’ve ever used Twitter, you understand the power of limiting words). Thus, every time you watch a video you can have a slightly different experience as the comments change.


There are quite a few cultural implications for why bullet comments have taken off in East Asian countries:

  • East Asian languages like Chinese and Japanese are symbolic by nature – more meaning can be packed into less space (ie I love you vs 我爱你; 10 vs 3 characters).
  • East Asian people tend to value collectivism over individualism – their individual expression leads to collective identity.
  • In China specifically, the One-Child Policy has resulted in almost all Millennial/Gen Z children growing up without siblings – thus hungry for peer company.

Beyond East vs West comparisons – humans in general seek companionship and tribes. While loneliness is a problem in the US (especially amongst elders), it is still a taboo topic. This contrasts with the East, where it is not. In Japan, females will “rent” boyfriends and males will go to “cuddle cafes.” In Korea, Mukbang streamers (people eating on camera) make millions annually. Loneliness is an open “problem” – and bullet comments are a continuous reminder that people are “not alone”.

Mukbang - Wikipedia
A Mukbang streamer eating in front of his camera

While the desire for companionship is a fundamental human need as old as time itself, bullet comments also appeal to a learned behavior – media multi-tasking. Since the advent of mobile devices, attention spans have significantly shortened and multi-tasking has become pervasive. (Next time you’re watching a tv show or movie, pay attention to how many times you pick up your phone). The bullet comments present a fast-paced novelty that keeps viewers honed in on the screen.

Beside taking advantage of cultural behaviors, bullet comments are also playing a role in *creating* new culture.

  • There are numerous examples of content going viral not because of the content, but because of the bullet comments associated with it
  • Artists have started creating “bullet comment art” in the form of short stories, poems (text) and shapes, drawings (colors, animations).


 While other video platforms have bullet comments, Bilibili separates itself in terms of *who* can submit the comments. Other platforms simply (and thoughtlessly) gate bullet comments as a paid feature, whereas Bili takes them as an opportunity to sift out those who can earn the privilege through passing a 100 question membership exam. Testing for culture and etiquette, Bili is able to select for people who are willing to sink significant time to pass which tends to filter out spammy, offensive, or misaligned comments. Bullet comments by nature invoke feelings of participation, but it is the *quality* of Bili’s bullet comments that makes it stand out from the rest. In fact, right next to the “send” button, Bili has a reminder linking to “netiquette” – or Bili’s commentary code of conduct. 

The participatory nature and quality of Bili’s bullet comments makes people want to join the community. Whereas people on Reddit simply lurk and never sign up, Bili viewers are compelled to get involved. This is evident in the 100mn official members who have passed the 100 question exam in order to send bullet comments and feel a more ingrained part of the community. (In some ways – this is similar to China’s GaoKao. It’s a test everyone in China has to take that assesses their baseline level of education. Some interesting implications here, but out of the scope of this note).

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Chinese students taking the GaoKao

Recently, Bilibili filed a patent to allow for “red packet bullet comments.” For those unfamiliar, traditionally red packets are monetary gifts that are given during the new year. Online, they represent small monetary transactions. (WeChat, who popularized them, limits transactions to 200rmb per transaction). Livestreamers commonly receive virtual gifts (such as a “purple treasure chest”) from their viewers, however, there is not yet way for streamers to send gifts to viewers. The patent would allow streamers to gift out packets through the bullet comments, where if a user clicks a bullet comment they receive a small amount of money. This helps reinforce the community and makes the livestreaming more interactive. There is also a neat marketing use case, where streamers can say – “Giving out red packets – make sure to tune into my stream between 9:30 and 9:45 for a chance to get some free money!”). Can you imagine what Mr. Beast would do with this functionality? It’s also already a proven marketing method; as any WeChat user can attest, group chats are filled with people asking for “favors” and volunteers and incentivizing responses by sending out small red packets.

Earlier, we wrote about how bullet comments are playing a role in creating new culture. However, it’s not just creating new culture, it is a new medium in and of itself. The combination of bullet comments and underlying video content is different from just a video. It’s a way for viewers to enjoy a new experience every viewing. It’s a way for fans and creators to collaborate on creating new content. It’s a way to encourage viewers to become creators.

There’s actually an interesting flywheel here – Bilibili uses content to attract viewers. Those viewers will watch videos with bullet comments. Watching those bullet comments will stir up the desire to use the bullet comments. That desire leads users to taking the membership exam. After taking the membership exam, the users begin participating in the creation of content through remixing videos. The more they participate in this content creation, the closer they become to uploaders themselves. And if/when they do become uploaders, they create content that helps Bili attract more viewers.

Concluding Thoughts.

While Bilibili’s one-two punch of community test and bullet comments has cultivated a strong community, it has not grown without any concern. But that’s for another time. If you want to be updated when we publish our next Details and get notified when we publish our next full report (which will be free), sign up for Free Updates below!

Special thanks to Avery S. and Rui M. for reading early versions of this post and providing invaluable feedback.

For the free full deep dive on Bilibili, click here. Future reports will be exclusive to subscribers only, but our Details emails will always be free!

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