Last I heard mozilla browsers were avoiding official h.264 support. Also google is speaking of officially pulling h.264 support in Chrome:
http://blog.chromium.org/2011/01/htm...in-chrome.html
As an affiliate I can't tell you how many sites I have been unable to promote fully because the promo material offered was in a format which I was unable (or unwilling) to use for one reason or another. Why not offer everything reasonable? After all you convert it once and thousands of affiliates have it. The effort should pay for itself, no?