It would be really hard for blizzard

It would be really hard for blizzard to have these videos for healing and tanking specs, since they are specs that are based on reacting. Healing requires you to assess the situation and respond accordingly (same as tanking I guess), whereas DPS can (at least sometimes) say acheter wow gold"do this and you'll perform decently".

This wouldn't be impossible to do, but would not fit into the "Crash Course" video section.