EXTERNAL SOURCES FOR GAME DOWNLOAD.

This is somewhat trivial, but I think it might be nice to give the option of using an existing download source when creating a download for a game rather only being able to upload one. It doesn't even need to give the link of the original source. It'd save the site some bandwidth, and make it more convenient for those who have a direct download source where they can replace the file with fixed versions and the like in one place.

Again, quite trivial, but just putting it out there.