"if you distribute h.264 videos on a large scale (&#62;100k viewers), you need to pay licensing fees."<p>Clearly, the likes of Youtube and Vimeo don't care about this. They do seem to care about using a codec that is standard, widely supported and with good and varied implementations (both encoding and decoding, with or without hardware acceleration). Theora has neither of these characteristics.<p>"Only if you use the OS' native decoder, you don't need to pay. But Firefox is multiplatform. WinXP, Linux do not support h.264 out of the box."<p>Well, WinXP and Linux do not support Flash out of the box, but that doesn't seem to pose any problems.