For better results, adjust your Quicktime settings to prepare videos for internet streaming...
Is the message I'm getting with all my V12 Sony AVC mp4 uploads to YouTube now.
My vague and hazy understanding of this issue is that there's some sort of bit that quicktime can set to optimize streaming, but which Vegas won't let you set. I've been assuming YouTube does this during conversion, and that there's no real quality hit versus uploading a compliant file, but I haven't seen any recent conversation here on the subject.
Can vegas set the fast start flag? Does it matter?