I remember somewhat recently that YouTube was using the H.264 codec for their videos in HTML5 format. This is a proprietary format, and Firefox is open source, so they only support Theora and Ogg ...
I currently use Google Gears with Gmail and Google Calendar to keep an offline copy of my mail and calendar. I use Firefox 3.6, but I'm looking at upgrading to Firefox 4. I read that HTML5 has ...