it depends on the converter your using, hes using FLV to AVI MPEG WMV 3GP MP4 iPod Converter i think
get xilisoft HD converter. Im Sure u can get it for free. Convert ur files into HD WMV format. Put it into vegas and to each clip add the following
Saturation Ad- Boost Midtones
Color Correction- Studio RGB to COmputer RGB
Than render it at 640-480.
Also for full screen use track motion.
I will help, hit me up on my gamertag AnonymousBTARDs