One of the problems with the built-in upload functions is that the websites in question often change the procedures and protocols for doing the uploads. It is often reported that within a few months of a new version of Vegas coming out, the upload functions no longer ... function.

I never really understood the necessity for them anyway. It's very easy to render a finished video file to your hard drive, which most of us do all the time anyway, and then log into Facebook and use their upload function. Done. That way you always get the upload function that facebook/youtube/vimeo/whathaveyou want you to use and that works.