Last I checked Chrome's h264 had less accurate color presentation than most off the shelf flash decoders. I can't seem to recall how Firefox's webm decoding stood up when the file was comparatively accurate to the h264 the flash player was using.
No reason to be hostile. We investigated months back when we got reports from our users, who are professional videographers, that videos were showing up much worse in some browser situations than others. They sent us screen shots, and upon investigating found that on almost every clip we were getting better results using two different flash players we had access to than the native decoder.
I don't have some big official report because, well, that's not my job and I have better things to do. You're welcome to investigate yourself if you're concerned about it.
Here is an example of a Firefox bug report about H.264 color spaces looking different in Firefox compared to another video player. So these are real problems. :)