My average is just under two hours a day according to the app (tbh some weeks think it's more than that though). Some of that is actual 'watching' time and some just 'listening' while doing something else.
Channels I like watching include various 'educational' ones and stuff others have mentioned, also enjoy:
Historia Civilis (Roman history)
History Time (history, I like the ancient history stuff)
Curious droid (random interesting topics)
Isaac Arthur (future space technology etc)
Matt's offroad recovery (episodic rescues of people stuck on the trails of Utah)
GTOger (random goings on and people getting towed off a parking lot in Dallas)
Atomic Shrimp (scam baiting, plus loads of other random stuff)
Call me Kevin (funny and varied gaming videos)
Also a bunch of more niche channels that do stuff related to A Song of Ice and Fire / Game of thrones (eg Preston Jacobs), and hill walking & Trekking videos (eg Scotland's mountains).
I go through phases too, where I'll discover a new topic and watch videos about that for a while then move on. Eg recently started watching videos about theme parks and roller coasters (channels like Defunctland and ElToroRyan). Before that it was 20th century warships (eg Drachinfel).
There's so much on YouTube, could (and occasionally do) spend all day on it! Find most of the channels I'm subscribed to so much more compelling than most stuff on broadcast TV.
What's dodgy about his background?
He comes across as really nice and as far as I know he used to run a hotel which went bankrupt in India or something.
If you Google it there are all sorts of dodgy stories around about past behaviours, youtube videos covering it as well.
Have you watched his first ever (at least first one still on his channel) video? Personally find it really creepy, bit of an insight into part of his mind perhaps. Especially considering the stories about potential sexual misconduct, shall we say. He does / has done collabs with people who have strong 'dodgy' undertones too, eg Irish partizan. Odd that these people seem drawn together.....
There's arguments to be had about what's just conjecture based on circumstances and unverified stories and what seems likely to be true, but personally couldn't watch any more of his videos and enjoy them after some of what I read. Aside from the baggage, once I started thinking about some of what he says and does with a less sympathetic eye he just started to come across as a bit thoughtless of other people and a bit of a ****.