Firefox doesn't do that, your NSAPI plugins do: on Linux there are plugins that wrap mplayer, vlc, or totem supporting the quicktime API in widespread use. Unfo

Firefox doesn't do that, your NSAPI plugins do: on Linux there are plugins that wrap mplayer, vlc, or totem supporting the quicktime API in widespread use. Unfortunately all of them suck terribly -- seeking is always broken, they always find a way to do the wrong thing wrt progressive download, weirdass YUV->RGB artifacts after dropped keyframes, etc. You could write a new NSAPI plugin using ffmpeg that provides the <video> API but proxied through <object>, and package it in an XPI along with some greasemonkey-style extension code to rewrite the tags and provide the default playback UI.