H.264 vs. WebM is a far more nuanced tradeoff – widespread support and higher-quality implementations versus [hopefully] freedom from patents. Either way, the web wins if there's more <video> and less <embed> depending on an opaque binary blob from a single vendor with a track record of platform neglect.
You say "no extra effort", as if widespread platform support, hardware acceleration, more than one high-quality implementation, significant support by authoring software, and direct-to-format hardware capture would happen for free. Avoiding royalties would be nice - although it's almost certain we'd still have lawsuits absent patent reform - but as a business decision that's a LOT to give up.
I really think Mozilla did the web a disservice. They should have implemented platform codec support immediately and added other formats so content vendors could adopt HTML5 video independent of the codec wars
And that's one of the biggest problems with software patents. In 15 years, we'll likely be using a different codec (or, at least I would hope we'd make some progress in that amount of time).
On the plus side, the situation is much less dire than it was back when Mozilla first made the argument against H.264. WebM is a serious alternative, and if MPEG LA tries anything funny, people will be able to switch.
Unfortunately, WebM isn't _really_ a serious alternative. It's a fine codec and produces great quality video in a similar filesize to H.264, but it's not supported on the majority of mobile devices. H.264 is also what many consumer video cameras produce, like iPhones and most DSLRs.
Pragmatically, I'm happy that all the major browsers (with the exception of Opera) will now support one common codec, even if it's patent-encumbered.
Depends on the threshold for calling something "serious". It's far more serious than any alternative before WebM, that's for sure. No competing format will ever be an instant drop in replacement for an entrenched format, but there is a continuum of scenarios below that.
I hope content publishers will find publishing HTML5 video convenient enough to drop Flash. Once publishers are all on board the HTML5 video train, they have the opportunity to experiment with new (and unencumbered) codecs without affecting their user experience.
