Which music YouTubers’ have had hit records?

Jfingers

Arctic Monkeys gained a lot of early traction on myspace. They can shift a few units.

EricTheWeary

hollywoodrox said:

Tim pierce definitely  “runaway” solo 

Some of the guitars on Iris by The Goo Goo Dolls which held records for airplay in the USA, top ten hit, hit in other countries,etc. Just not that well known in the UK. 
He plays rhythm guitar in some of the more recent Santana stuff and was one of the musicians on a recent Bob Dylan project. It's on YouTube with attractive young people miming the parts, the  comments section saying oh what talented young people and explanations that what they are actually hearing is sixty year old studio hacks.