Another addition to the above excellent list is "bigclivedotcom". Lots of teardowns of cheap Chinese electronics with an eye towards what exactly makes them dangerous. https://www.youtube.com/user/bigclivedotcom/videos
Clive is the best. Sometimes the cheap eBay gadgets get a little repetitive, but he does mix in a lot of different stuff. I really enjoy his videos on printing circuit boards and making his little 'nixie' lamps. He's just fun to listen to.