Yes, it was a towbarless "supertug". The DC9 was being moved from the hangars to a gate when this happened, and I think it was being turned into a gate towards the end of the E-concourse. This would take 5 minutes or so to accomplish based on the speed of these supertugs. Conditions were freekin' cold with temperatures around -5 deg F with a stiff wind out of the northwest giving a windchill factor of around -20 deg F. This is very cold even for MSP in the midst of a cold spell. Ramp conditions were basically clear and dry with some icy patches.
NWA have only this last year or so begun using these super-expensive supertugs in MSP. They have also this last year changed from having Mechanics tug the aircraft around to having trained Ground Service Personnel perform this task. Of course they also have someone in the cockpit during these tows.