bullet screen 弹幕

"Bullet screen," or danmu, a model of movie-watching that has been introduced in select theaters in China since 2014 has been widely used by video websites. 

2014年开始在中国部分指定影院引入的“弹幕”其实早已被在线视频网站广泛应用了。

In this case, the bullets don't refer to actual bullets, but to text messages that audience members send via their mobile phones while watching the film or video. The messages are then projected onto the screen, so that at any given time the scene may be overlaid with multiple "bullets," or comments, scrolling across the screen. 

这里的“弹”并不是真正的子弹，而是指观众在看电影或视频时通过手机发送出去的信息。这些信息发送之后都被直接显示在屏幕上，所以，观看电影或视频的时候，你随时都可能看到整个屏幕上挂满了滚动显示的“子弹”，也就是评论。