The following is an article on setting up a split tunnel on your vpn connection(using the windows network connecton method).
http://www.microsoft.com/technet/community/columns/cableguy/cg1003.mspxBasically you aren't making the vpn connection your primary gateway like windows does by default. Instead you are telling it to only send thing destined to work through the vpn allowing you to view streaming media through your home/wherever connection. To be completely honest, I haven't read through this in detail or tried it out myself. I have all of my workplace setup using the cisco client against a cisco PIX for vpn connections which does this automagically(well automagically on the user end... not mine).
If anything doesn't make sense I could probably look a bit more into this and explain it at a meeting sometime.