I prefer visual (DVD) also as the preferred way to learn, but after searching the web and other literature the most recommended source I found was a book:
“Wilderness Navigation” by Bob and Mike Burns, printed by the Mountaineers, in Seattle.
It even has sample problems in the appendix to make sure you have learn the information.
I checked it out from the library and after reading it I purchased the book for my personal library.
It’s the best I’ve found on the subject