Note that there is an error in this video at (mins) 3:23 mins. From G1 to H should be your Shoulder Length + 0.5 inch dart. (If you follow the instructions as is, you will end up with Back Shoulder Length shorter than the Front Shoulder Length. At some point I will redo the video and correct this mistake.
The other videos in this series are:
Drafting the Pants Block, Part 1: Introduction & Measurements