51:35 duration 51 minutes 35 seconds
Lecture 18: Clouds 3
02:05:47 duration 2 hours 5 minutes
3.5, 3.7, 3.9
01:59:11 duration 1 hour 59 minutes
2.8, 2.9, 3.1
02:00:48 duration 2 hours 0 minutes
2.1 and 2.2