Another REALLY good HTML5 video player (if you're not interested in using clunky, stinky Flash), is called "VideoJS", and can be found here: http://videojs.com/ .
Nice I actually haven't heard of this. I would have suggested FlowPlayer like I used years ago (before HTML5 was becoming standard), but this seems like a much better option!
MKV is not a codec though, it is a container. You're confusing the two.It's a shame not every codec has the compression ratios of mkv's :[.