I had no idea I had so many artist subscriptions on You-tube until I looked!
Stefan Bauman has some wonderfully inspiring art talks, but not about watercolor.
Deb Watson, Anna Mason, Anita Gazinska and Joanne Sharpe all provide great lessons.
Strathmore Artist Papers has some great tutorials that I have learned new techniques from.
And lastly, because I use Peerless Watercolor Paks I found some good info on using and storing them with Jennifer McGuire Ink.