The time limit includes the time it takes to watch the video. In the first 10 lessons or so, some of the lectures are 30 minutes because they cover basic or easy to understand concepts but the practice set questions are easy and can be completed much faster. After that, most lectures are only about 15 minutes. Be sure to read the Instruction Sheet for Lectures linked above each link to a lecture.
See these articles for detailed information:
Time Saving Tips for Success
The Timed Method & Fluency