pretty simple leslie,
Use Vegas to render to AVC .mp4 using either the Sony or Mainconcept encoders.
Then convert to .flv using "Almost Any" converter. There are lots of them out there, some free, some costly, but use the one that works best for you.
I've used the on2 pro encoder. It's a bit pricey, moreso now that I can do it using Adobe's media encoder. I don't know how the quality compares but at least Adobe's encoder is simple to use and doesn't crash for the oddest of reasons.
I use On2 Pro and I found that is was faster than at least Adobe CS3 when I convert plain DV AVI's to FLV.
I like it a lot and you can actually make a small set of html file, player and the FLV to make a preview on-line for client f.ex., but as Bob point out it's not the cheapest arround.
funnily enough i use super with my students all the time (they record in all sorts of formats), but never ever thought of it for swf/flv - which i just tried and by golly, it does a reasonable job - though that's not knowing what can be done with any of the other software mentioned.
anyway, it's good enough for what i need at the moment (banner on web page from m2t)...
A point worth considering was brought home to me by an article by David McKnight in the latest issue of EventDV mag.
Now that the penetration of Adobe's flash player v9 and v10 are so high and since these versions can play MP4 content, a separate Flash encode step may become a thing of the past.
It is extremely simple to embed the JW Player (Flash player) in a web page to play MP4.
Take a look at this sample of a Flash player using MP4 content here - http://www.jcdv.com. Link is from the above mentioned article.
That's certainly a big advance, but the proliferation of MP4 capable players may not be as great as one would think -- yet.
For the time being, maximum compatibility will continue to be with Flash extensions; many people simply don't update their players, or browsers for that matter.
I use Iamtoo Mpeg encoder software it costs about 50 bucks. You can see the results here: Very easy to use and will allow you to convert to over formats also.
qactv.peg.tv
just type in address as above and all the 16x9 video was M2t. most of the videos are over 2 hrs long on the web and run great.