I'm Rémy from the SublimeVideo team.
I've noticed a bug that is very annoying and blocking. Indeed it seems to prevent Firefox from playing a video.
The issue comes from the fact that you're generating the <video> tag and <source>s tags in a big multiline string with tabs in it. Unfortunately, it seems that Firefox transforms the multiline with tabs in <p> elements, thus putting some <sources> tags in <p> elements. The problem is, while doing this, this browser doesn't succeed to play the <source> when in <p>. I've setup a simple page to show you what I mean (with and without SublimeVideo): http://test.sublimevideo.net/source_in_p
Could you please generate a <video> and <source>s elements without those unnecessary and problematic newlines/tabs?
Thanks in advance, hopefully we should release our official plugin sometime soon during the summer, but it would be great if you could fix this in your plugin in the meantime.