It's an RGB laser projector using active controls to create the show. I used something similar my first time doing a laser show. Though it was to music, with active beam elements. This is him controlling a static beam to move to waypoints set, that he also placed triangles over.
Notice how they start flickering? This is because he has placed many triangles, and the projector takes longer to get to them. All of the patters created by projectors are done with VERY fast moving mirrors, moving the beams around, via a computer interface. In this case, he is telling the 100% static beam to go to every balloon location. For dramatics, he is placing triangles in the program so it looks cool.
This could have probably been done faster, though balloons don't pop instantly.