It could have been done in 3 different ways that I can think of right off the bat.
1. He did his dialogue once, with a few cameras set at different angles.
2. He did his dialogue many times exactly the same (rehersed) with one camera many times at different angles.
3. He did his dialogue in front of a green screen and used a program, Vegas Video, Final Cut, After Effect, etc. to move and zoom in his video at different parts and cut it all together.