This is a music video for the song "Ritalin" by techno band Dancing Pigeons. It depicts two men armed with a flamethrower and a fire extinguisher shooting at each other. Director Tomas Mankovsky wrote about the challenges involved in making the video:
It was difficult to know how this shootout would look like in superslowmo. We did some tests with a gas-flamethrower but the flame was only 2-3 meters and it looked quite bad in slowmo, so the special effects guys had to build a new flamethrower from scratch. They made one with liquid fuel, and that one was much better, firing out 10-15 meter flames. But the first time we saw how the flamethrower and fire extinguisher looked and behaved in slowmo was on the day of the shoot.
Link via Geekosystem | Band's Website | Director's Website