There’s something grounded in a very particular kind of 1980s/90s BBC Television content in the values Tom Scott’s videos embody. It’s sort of like he managed to give himself a job roleplaying as a Blue Peter/Tomorrow’s World presenter. He basically carried forward the kind of Reithian ‘mission to inform’ BBC values that largely disappeared in the John Birt era and somehow brought them onto YouTube.
IIRC in one of his videos, he explicitly said he was modelling himself on the Blue Peter style he grew up with. If I had to guess, somewhere in this video, but I'm not watching 17 minutes again even at double speed just to make a comment: https://www.youtube.com/watch?v=mUF4afxMpQk
He tried and AFAICT failed to do TV in the past — this is probably not a bad thing given how the tides have changed.
I have always found his patterns of speech interesting. Quite measured but untrained.
I've never met him but I know a few people who have and I'm told that he's exactly the same in person (at least at a formal dinner!) which probably tracks.