The guy who does the wedding videos is quite write. You will need a software suite that supports multiple Video tracks (Adobe Premiere Pro or Ulead MediaStudio Pro and no doubt Vegas). On top of this you will also need software to support video Mattes.

Check out Marc's Peter's link on Video Editing at

http://www.videoeditingforums.co.uk/viewtopic.php?t=548

to check out the specifications of the main products.

Good luck!