Tom Lipton (Oxtoolco) had loads of really interesting videos towards making an etching press which includes a wobble drive speed reducer thing and a huge steel hand wheel.
I follow many of the usual suspects mentioned previously. There is however a fella who demonstrates some very good sheet metal skills, who I don't think has been mentioned yet in this thread, called "Lazze". He is promoting the stuff he sells but the tutorials are first class. Like Doubleboost and others, he makes what he does look deceptively easy which is encouraging to the likes of me but very misleading at the same time....
He has been quiet for a while until recently but he's uploaded a couple of new videos in the last few weeks. Spend and hour or two watching him and you may start convincing yourself you can build the body of a '32 Ford from scratch. I find I am very suggestible...
Bit of a thread resurrection but I have found a new (to me) Youtuber that I find really interesting. He has a very relaxed style and there's none of that crappy heavy rock music that American Youtubers seem to like so much just because they are able to lift a wrench.
The channel is called Mustie1. Amongst other things he picks up gardening equipment for cheap or free and diagnoses and repairs. I find him very interesting and have learned a fair bit. I grew up with electric mowers in the household so all the fettling of two stroke and four stroke small engines is quite educational to me. He also manages a very respectable welding repair on a Toyota Tundra Chassis rail so all you Landrover enthusiasts have something to relate to. He is the typical bloke pottering about in a garage and he seems to know his stuff.
I've seen Covell and Lazze but only the odd vid my dad put me onto them as he is into bodywork. Most of my viewing is music or bike related (mostly German sport bike tomfoolery).
Teng84
Vecci87
MrFunRacing
GMW (Germans Most Wanted)
Quickshift
Meddes
VerticalHooligan
44Teeth (Barron Von Grumbles new channel with Alaistair Fagan)
Lockk9 TT stuff
The Crumble
Power Drift
Lambchop Rides
Rnickey Mouse (bike crashes on Mulholland)
Clickspring
Metal tips and tricks
Myford Boy
Surburban tool
Dorite fabrication
Ted Talks
Bruce Witham
Stefan Gotteswinter
Shadon HKW
Randy Richards
Nick Colyer