High voltage and high current.
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In this video, he gets a new toy -- a transformer that is positively a monster compared with the old microwave transformer he had been using. The sheer size of this thing is daunting, but then he plugs it all in and starts playing. After some impressive light shows, he attaches a washing machine motor to the new toy and pushes it beyond its limits. The streaks of light visible within the case are quite pretty, but when it failed mechanically and started bouncing toward that massive transformer, I had to hold my breath.
Luckily, everyone survived, with the exception of the motor.
A CRT doesn't stand a chance.
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This poor television never stood a chance. These people go nuts and pump thousands of volts through a standard CRT. They may have left the room to be safe, but the camera stayed behind, and the results are revealed to us in real-time.
I could go on and on and on, but there are 119 videos on his channel currently, so I'll just stop now and suggest that you go there and browse around. Surprisingly enough, none of them include him catching that carpet on fire and burning his workshop to the ground.