The instrument is, in general terms, a MIDI controller. (MIDI is a collection of data that tells the instrument what sound to make when it is triggered.) More narrowly I think we could call those percussion pads. When the guy describing the contest says they're offering a 64 sample rack, he's talking about a grouped collection of pre-recorded sounds that can be manipulated with software and assigned to a pad on the controller.
The software they are using is called Ableton Live. Unlike other audio software that is designed for mixing recorded tracks, Ableton Live is meant to facilitate live performance. What it's like: How To Start DJing In Ableton (Part 1)