Actually most any wide grip row (BB,DB or Cable) hits the rear delt very well. That is, if you keep the BB/DB in line with the shoulders area through out and the elbows out wide. Even standing wide grip Hi-pulls affect this region, BB or DB. Including a few sets of a wider grip, in a normal back workout, can make a lot of difference. Just me, but I prefer doing one arm at a time DB work. Seem to get better focus on the side that is working.
For a lot of guy's the most effected rear delt exercise is on a Pec Deck, where the elbows are on the pads. Gves more direct effort, and leverage, to the rear delts. Keep elbows high and inline with the shoulders.
Good video, Cook gives ease of instruction. The lying bench exercise (5min, etc) has been around for awhile. Some do it on just on a floor mat. Excellent point he makes is that you do not have to raise the DB all the way up.
Can work the lateral head of the delts this way (bench or floor) by starting the raise with the DB lying in front of the body. Than lift it to about 3/4's of the way up and than lower it behind the body, all the way down. Now raise from behind the back to the 3/4's mark and lower to the front starting position again. That is one rep. Nice results for some. Good Luck.