You can actually control the buffering/playback with JavaScript. There are various ways to do this; one is with the TimeRanges object http://www.whatwg.org/specs/web-apps/current-work/#normalize.... which will give you a representation of available time regions in the video resource.
I could understand this in mp4, which has a global index giving locations of all frames in the file, but how would this be possible in ogg, which has no global index? Without a global index, you can't know anything about time regions that you haven't yet downloaded.
I could understand this in mp4, which has a global index giving locations of all frames in the file, but how would this be possible in ogg, which has no global index? Without a global index, you can't know anything about time regions that you haven't yet downloaded.