That is weird. I seem to still have the option on my side. As unlikely as it is have you tried clearing cache/cookies and reloading the site? Sometimes I'll get really weird glitches in chrome when I don't clear my cache regularly.
Edit: I also don't have the latest version of chrome either yet....so that could be why.
@rorie: Well after doing a quick twitter search for "Chrome HTML5" I did see a number of people tweeting about not being able to play HTML 5 videos on other sites after the most recent update. So, it may not be a site thing at all. Could very well be a chrome thing.