Mike's Electric Stuff was uploading stuff back in April 2007, but videos where he talked weren't until 2010 by the looks of it.
Fat Man and Circuit Girl had a live show back in at least 2008 I think.
I don't recall other names off-hand.
I wasn't the first with electronics, but I think maybe the first with a "video blog" style regular electronics channel. Certainly the first to go full time at it in April 2011.