Bullet Chatting refers to comments or an annotation floating over the video in certain way at a specific point of time of the video. The Bullet Chatting proposal is described in a family of sub-documents. This document is an index for the documents.
This is still a work in progress. The proposal is being incubated in the W3C Bullet Chatting Community Group.
The introduction and use cases of Bullet Chatting is described in the Use Cases document.
The technical proposal for a standardized way of adding Bullet Chatting to the Web is described in the API document.