How many formats do I need for HTML5 video?

I consider the HTML5 bible to be Mark Pilgrim's work-in-progress Dive Into HTML5 book, which is available online.<p>The part of the book that specifically covers this is:<p><a href="http://diveintohtml5.org/video.html#what-works" rel="nofollow">http://diveintohtml5.org/video.html#what-works</a><p>It's a great book with frequent updates and it covers everything, including local storage.

I recently started doing some tech-related screencasts for our clients (photographers) at <a href="http://bigfolio.tv" rel="nofollow">http://bigfolio.tv</a>.<p>I wanted it to be all HTML5 and I'm still experimenting. I ended up doing 3 H.264 versions (a large .mov and a large/small .m4v) and an Ogg file. Just to be safe, I put a couple download links for people.<p>I haven't had any complaints but I did notice that older version of iOS can't play it. Haven't really tested Android.<p>Getting them all converted and put on S3 is quite a PITA. Another thing I discovered–if you're putting Ogg files on S3, you have to make sure to set the mime-type or FireFox won't play it.

Just ran into the mobile issue with file bitrates being too high. There are a lot of "gotchas" when doing html5 videos, but not too many that would scare you away from using it, you just need to test for a lot of cases.

If I were doing this today, I would choose just x264. Deliver it via the video tag, with flash as the fallback for firefox.

Too many.

Is there a simple way to do live streaming with WebM yet?

No recommendation on the multiple bitrate settings? Anybody?

which of those formats can ffmpeg convert to?