Guardian Angel
Cooldown: 1.5 seconds
Fly towards an ally. While in flight, Jump launches you forward, and and Crouch launches you upward.
Resurrect
Cooldown: 30 seconds
Revive a dead teammate.
Valkyrie (Ultimate)
Needs to be charged
Gain the ability to fly. Abilities are enhanced.
In case the video won't load here's the external link.
A Guide for the Hero Mercy from Overwatch
The narrator talks about the hero generally then summarizies it's abilities and how you can use the effectively in the most precise but shortest way. In the background there are clips from the game, possibly it's the narrator's gameplay. He talks about against which heroes can and can't be this specific hero be used.