Very easy. I saw a thing about that. It is taken in different takes, not all at once and live. The ones from his point of view hiw he is suspended rom a rope, (you can see this because his feet go into hte water a little and look like they arent making contact with anything hard). For the other shots there are skinny poles in the water with platforms, (which you can see because his feet make hard landings and have solid stances). Why do you think he has "random" people in the water? They werent there to watch. They are a part of it to cover the other people from seeing the poles.
Also,
About the glass window one. That one is easily done with again, actors, and VERY clean glass. The window slides up, then back down. Simple. The key part to his stunts are the peole who pretend to be "random" spectators/helpers.