Assuming you're converting the FLV's to MP4's before you plug 'em into Vegas an edit, are you saving them back down as MP4's with that 720P Internet HD option? Or as an AVI with that 720P YUV (huge file size) option? Or if neither what else?

I tested a quick clip an saved 'em down as both of those and I don't think I even saw a difference between the save down of that internet hd option (9mbs) and the avi YUV codec (370mbs).

Side question. Does it matter how small or big a file size is when uploading to youtube in terms of how quick the youtube will load for viewers in 720P? Every once in a while I'll run into some vids that just take forever to buffer through, always wondered if it was because they uploaded a couple Gb file or what.