I don't know how AVI/MPG/WMV lost to FLV in the HD arena, but it's over. For a long time Youtube was a garbage dump of low-quality FLV videos, but it's changed so suddenly.
I refused, or at least resisted, viewing stuff on Youtube due to its frequent poor quality, given that excellent HD video sites like Vimeo were providing top notch stuff.
But now 720p and 1080p have become mainstream on Youtube, and on a long list of competitors, even Vimeo.
This means my list of downloaded 720p/1080p FLV files is growing, and I must say that it is quite unfortunate that Splash PRO is not able to play any of them at the current time. I had read in the forum somewhere about FLV being omitted from Splash due to it being "a low quality format" or something, but that reasoning sure needs to be updated!