Codecs are still a problem, though - there's no single universal codec supported by all major browsers. WebM isn't supported by IE, Safari and iOS, H.264 isn't supported by Firefox, Opera and possibly Chrome in the future.
It's a mess, and I don't see it getting better in the near future.
Right now, two codecs cover all the browsers that matter. Internet Explorer supports WebM, but doesn't ship with the codec; Google provides the WebM codec for Internet Explorer (https://tools.google.com/dlpage/webmmf). That just leaves Safari and iOS that still only support H.264.
Meanwhile, if Adobe would ever get around to adding WebM in Flash as previously promised, that would work as a fallback for Safari, as well as IE users without a WebM codec, leaving just iOS.
Safari (on Macs) has had a codec plugin support mechanism for codecs for a long time via Quicktime, and I believe WebM is already supported in Perian, the popular ffmpeg/libav wrapper for OS X.
Interesting, but that doesn't seem like something straightforward to convince a random site visitor to install. Google's WebM plugin for IE seems like a hard enough sell even with Google's name attached to it.
I doubt it's beyond their ability, particularly as someone's demonstrated that it can be made to work. I'm guessing though that they'd be generally happier if people on Mac OS X just used Chrome. There's less likely to be Safari users who are forced to use the browser due to IT department dictates or whatever other odd reason people use to justify IE.
It's a mess, and I don't see it getting better in the near future.