if you have a bunch of files that are AVI from the same movie. that means you have title menus also?
im not sure what youre trying to do here. because one large video file would be around 7 gigs.
i just googled it
i make copies of my dvd's a lot and programs like DVD shrink/DVDdecrypter can create one large ISO file.
if you just want to play all those files together at once, why cant you just select all and drop into windows media player?