Err, even at 512 you are only looking at about 3 hours for a movie(assuming 640 MB). I really doubt your cable is that fast unless you have a "business class" cable. I would guess 6 hours would be more accurate. It would be best to just have them get the movies and stuff from the same place you are getting them.
BTW, I used
http://www.visiongraphics-inc.com/tools/ftpcalc.html to get the transfer time.
I would probably try FTP, I would think it'd have the least amount of overhead involved.