If you strip away the author's bias toward "End of the World Survival" and his negative FCC bias, what follows is an excellent overview of several Digital modes explaining what they are and their best use.
The video is 51 minutes long, BUT... you can save time by stopping at minute mark 41:41
Shortwave: The Warlord's Radio
00:00 - Introduction
04:10 - The Emergency Itself
08:10 - The Nature of the Communication
10:26 - MARS Mod
14:24 - Mobility and Fitness
18:40 - Data Modes - RTTY
23:26 - Sending Images
28:37 - JS8Call
31:56 - Winlink
35:41 - Comm Scheduling
41:42 - Encryption
42:58 - Thinking Big
47:15 - Closing Thoughts
LINK