With MIDI files you are able to take full control of the loops on this site, move around notes, tweak and change the loop however you like. You get to play the loop with your favorite VST/sounds, getting the loop to sound exactly how you want it to.
MIDI files can be opened in almost every major digital audio workstation. If you need instructions on how to import MIDI files, pick your workstation below for more info. (external links)