He used a paperclip to deliberately override a short in a vintage machine's power supply, with predictable (bad) consequences, as I understand it.

A lot of people (not me) hate him because he destroyed a prototype IBM a few years ago trying to repair it.

the main technical side is as he has exploded on youtube he has basically became the defacto keynote speaker at most of the retro computing events. now he is quite knowledgeable in the commodore/vic/pet programming scene however a lot of his other presentations/ videos are collections of community knowledge that he has gathered . that comes part of the issue in the community freely shares tons of info for it to be greatly profited by a few. there is also many cringe at some of his videos where he is given access to rather rare items and doesn't follow 'sane' practices before applying power going as far as saying in one video he is constrained on time to release the video so with a high probability blows up a prototype pc power supply basically for purpose of providing closure to a video.

If it's not the questionable qualifications(although he is an enthusiast, he has a limited professional background in electronics repair and software development, two things that are constantly featured on his channel), it may be because of his gun-toting libertarian leanings - some years ago he accidentally posted a video where he was proudly open-carrying on a shopping trip. Of course some people voiced outrage.

I think the guy is good at making videos - but it's with an asterisk. He doesn't have a lot of expertise to share, but he wants to be seen in control. So the videos themselves are always really polished, but then the thing he does is something he should have asked for help with.

Definitely on Mastodon, was on Twitter before that.