My favorite exercises are #6 Working with Effects and #7 Working with Audio. My knowledge base was enhanced within these two areas. How to use varying effects to enhance your video and keep it looking professional. I especially liked the section on how to create green (blue) screen effects and how to correctly create a movie trailer.
Working with audio was very interesting. Especially how you can, not only adjust the levels for the audio but how you can replace audio on specific clips, how you can extract audio and even edit video clips to the beat of the music.