His blog is very insightful. There is also another great post where he talks about how to cheat on video comparison tests ( http://x264dev.multimedia.cx/archives/472 ). One of the things brought up in there is for still frame comparisons. If the frame came from an I frame rather than a B* or P frame in the output video, the test will be unfair.
*VP8 doesn't have B frames, similar to the h.264 baseline profile.
There's no doubting gasset-glaser's (DarkShikari) knowledge in these matters, but he is hardly an objective party.
Apart from being one of the developers of open source GPL licenced x264 encoder, he and the other developers are also licencing it for proprietary use (nothing wrong with that, I think it's a great way of making money out of open source development). This means that a open source royalty free codec like VP8 (and later VP9) could cut into their revenue stream.
I'm not saying that this affected the outcome of his test, but it's still context. Also his test back then was also criticized for only using one clip, here's another test with a larger set of comparisons:
That he has. My test clip choice was inspired by him[1], and I also link to another blog post of his[2] in the conclusion. That VP8 blog post is almost three years old now, though, and the comment I'm replying to in my article claimed that VP8 is better than H.264 "at this point". This is why I did my test with the latest and greatest encoders available for both formats today.
I think it would be more interesting to compare VP9 with HEVC (h.265), I know the VP9 experimental branch can easily be checked out and tested, but I don't know of where to find HEVC encoders (although I'm sure they exist with some Google fu).
Obviously there are problems with testing unfinished implementations, as:
A) they are generally VERY slow given that there's little optimization during the development phase, and these next gen video codecs are more demanding than the previous generation
B) a great deal of the quality comes from fine-tuning during implementation, not from the specification. For example x264 is a 'best-in-class' implementation of h.264, readily beating many other implementations of the very same specification.
As such, this fine-tuning is not likely to exist until the codec implementations mature, which likely means that what is available now of HEVC/VP9 serves only as very rough estimates.
*VP8 doesn't have B frames, similar to the h.264 baseline profile.