The flash spark codec is very inferior to wmv for a given bitrate. This is what is being used on many video sharing sites that use flash, because it is a free codec. Comes with super c, etc. I'd guess it comes with winnydows.

The flash VP6 codec is at least in the same league as wmv for a given bitrate. Not quite as good, but really pretty good. This is what you get with the flash app from Adobe. It's costly.

The VP6 codec can also be purchased (sorenson? on2?) for use in sorenson squeeze.
That's the thing - flash is the king of layer control. Nobody does layer control like flash. However. There is a new-ish MS technology meant to be a flash-killer, called silverlight that offers an xml development environment, great browser integration (if you happen to be running IE...), and automagic plugin updates to work cross browser cross platform, just like flash... but can also integrate WMV streams.

Very efficient workflow I use
 

I wrote a how to on my blog using Vegas Pro 8, Debugmode Frameserver and On2 Flix Pro (use version 8.500 - later versions don't seem to work correctly)

You can read the how to here

Cliff, many thanks for this. I had a fling with Frameserver a few years back but never really explored the possibilities. Looks like it might be time to dust it down.

Very much enjoyed reading other posts on your blog as well - I recommend others take a browse through - some interesting material and opinions there.