Those videos are pretty good.
The optical stabilization on my camcorder (vs your digital stabilization) may be a tad better but otherwise, there's isn't much difference in quality as far as youtube viewing is concerned.
What format are you using to upload to youtube? V9? I'm using Vegas Pro 8 as well and I can't seem to get smooth video playback on youtube. They look much better on vimeo but of course you can only upload 1 HD video on vimeo a week without paying...