I doubt it's safe to do what these guys are doing in this video, but it's fun to watch them use the guts of a microwave oven to illuminate and pop light bulbs and vaporize metal objects.
From Joey deVilla:
At the heart of every microwave oven is a magnetron, which takes your ordinary household AC (alternating current) and turns it into a blast of electromagnetic energy vibrating at 2450 MHz, or about 2.5 billion times a second. Those vibrations, when pointing at things, especially things with some water content, cause their molecules to vibrate more, raising their temperature and cooking them.
Inspired presumably by the twin demons of boredom and terror (Luhansk is in that part of Ukraine that Russia's trying to annex), Kryukov and Pavlov decided to see what they could do if they took the magnetron out of a microwave and pointed it at things. After extracting a magnetron from a microwave oven, they fashioned a crude waveguide out of a coffee can so that they could direct the energy emitted from it.