We all know what DivX is; we don't need a lecture on how amazing it is. The fact is, videos take up a lot of bandwidth (I've heard YouTube are spending $1m/month on bandwidth bills alone) and it's simply not viable to offer them - for free - in high quality. Besides, the majority of the videos featured on sites like YouTube and Google Video aren't very high quality in the first place. Flash video is much more compatible than DivX (>95% of web users have flash installed, whereas most of the general public have never heard of DivX) and, aside from the people who jump over backwards weaving through the source code to download the .flv files and re-encode them as something more friendly, it's not as immediately apparent how to download a FLV file compared to a DivX alternative.