Dunno, Adam; I've not uploaded any videos to anywhere, myself.
However, when I've uploaded photos I've always imported them into the Mac and tried exporting different file-sizes and formats. One or other has always worked. (My wife uses the Facebook plugin for iPhoto when posting on her Facebook page and finds that incredibly easy to use.)
I'd suggest importing to the Mac; making a copy as a backup; fiddling with the video formats; persisting.
You come across as the sort of young man with persistence and a fair amount of technical ability: I bet you'll solve it soon.