And even those customers were hardly satisfied.
Facebook used to use VP6 before they switched to x264--from what I recall hearing in my time there, the On2 software was a disaster. Unreliable, slow, and overpriced--$1500 per core per year!
From my experience, the primary reaction of many companies to the announcement of Flash H.264 support was not "yay, we can save bandwidth with H.264", but rather "oh god now we don't have to deal with VP6".