I think either the video could be incorrect there, or Anet might have changed the mechanics, since its only very early in production still.
The official wiki states that the main hand weapon determines three skills not two, and Arenanet have said in their previews that there will be a dedicated slot for both a self heal and an elite.
But ofc its still nowhere near finalized so it might be changed.
Water magic is looking brilliant though, healing, snares, and damage, but I will assume that it will do a lot less damage than fire and air magic do.
Fire = full DPS and high degen from burning
Air = Strong DPS with stuns, blinds and knockdowns
Earth = Decent DPS and tanking
Water = Mediocre damage with healing and snares.
The best places to get info from are the GW2 website and official wiki ofc, Anet developers and CM managers have already identified lots of mistakes on the forums that reviewers keep on making.
Another point to make with the self healing is that the Phoenix spell also self heals. It flies towards the target and works in a boomerang manner, returning to you in a wide arc if you move left of right after casting it. After it returns it heals you, so why with so many healing skills already placed in the left 5 skills do players need to be forced to pick an extra dedicated one if they are playing in an area that doesnt need it?
The videos in post 183 seriously make me even more impatient now, I NEED THIS GAME no matter what the skill bar restrictions are going to be like.