The HTML5 spec was updated a while ago, I couldn't find any bug tracking that so this is not connected to a master-bug for it. Anyway, I'm pushing startOffsetTime because I need it for my webapp :-) You also need to fix your startTime, because now it doesn't conform to spec. This was my original bug (use case) to the WHATWG and browsers: I stream conferences using Ogg Theora+Vorbis using Icecast2. I have built a site that shows the video and then automatically shows the slides (as PNG files) as well. I use orbited (COMET) to have the server PUSH my «next» presses on my keyboard. The problem is that icecast does heavy buffering, and also the client, so that while I switch the slides, the browser will go from slide 3 to 4 WAY too early (from 10 second to 1 minute). If I could get the timestamp OR time-since-started-sending/recording from the ogg file in javascript, I'd be able to sync everything. There are multiple way to sync this, may even an stream with the slide-data INSIDE the ogg file, however, AFAIK there's also no way of getting out such arbitrary streams.
Can this be confirmed?
BBC blog post regarding their implementation of this in Firefox: http://www.bbc.co.uk/blogs/researchanddevelopment/2012/01/implementing-startoffsettime-f.shtml