At least that's the point of this post by Mozilla's Robert O'Callahan:
Most importantly, if we'd caved, the Web everywhere would look like it does in China and South Korea, but more so --- dependent on ActiveX, and tied to Windows. No resurgent Apple, no Linux netbooks, precious few Linux users, no ChromeOS, no iPhone, no usable browsers on phones at all, and Microsoft's grip on the industry stronger than one dare imagine.
O'Callahan also has a pretty extensive list of arguments in support of Mozilla's decision not to support H.264 encoded video in Firefox. The gist of it is that the H.264 has patents associated with it, and those patents are being licensed by MPEG LA. Mozilla has strong interests in keeping Firefox free, and so widespread HTML5 video usage on the web is at a standoff between convenience and freedom.
I support Mozilla here. Even though I don't want to wait another minute for the day I can stop using Flash to play videos, and as a developer for the day that we have a uniform, standard way of displaying video on the web, I think they're right in standing up and taking the fight now, as opposed to five years down the road when we're all stuck with H.264.