On Tuesday of this week, Michael Arrington of TechCrunch pointed out on the TechCrunch blog that Wal-Mart had mistakes in the code of their brand new video site that prevented the CSS from loading in Firefox. The blog post has a screenshot of what it looked like. It would appear that whoever designed the site did not even check it in Firefox before launch, and reportedly the mistakes were easily fixable.
Well, today I just went to the site and found something that you will not believe.
I think it depends on support of Windows Media Player and DRM. My ISP offers video streaming for their customers and they have the same problem with firefox-support.