Not everyone learns the same way, watching a video for me really does nothing, it in no way shape or form prepares me for what it is like to watch health bars and the encounter, what a lot of people fail to realize is not everyone learns the same way, some of us learn by doing, and no video is going to give you that.
Also lag plays a part in every encounter, no video can teach you that you need to do x, y amount of seconds before it happens to account for lag
You can still understand mechanics.
When op said "Any tricks or etc.." he was referring to boss mechanics he should be aware of.
Of course watching a video won't give you an understand for how YOUR group will deal with the encounter, and there's never a healer rotation.
You still will know when there are big drops in health pools from boss mechanics or times when there may be drops in health pools if people don't follow the fight mechanics perfectly.