Shoulders

Rear Delt Flye

Weighttraining.guide bent over lateral raise
Colussus Fitness rear delt fly
John Meadows on dumbbell rear delt raise
Mike Thurston and Ben Pakulski on rear delt flies and other rear delt exercises (they show very nicely how to change angles to put the focus on different parts of the muscle)
Mind Pump on rear delt fly
John Meadows shoulder workout with dumbbells
Dr. Mike Israetel on rear and side delts (good stuff on volume and ROM)

Barbell High Row

Jeremy Ethier on alternative rear delt exercises, including the high row

Dumbbell Press

Weighttraining.guide dumbbell overhead press
Moji Oluwa on dumbbell shoulder press
Jason Gallant on how to get the dumbbells up (also talking on when to go light, and when to go heavy)
Bryan Renshaw on how to avoid shoulder impingement
Colossus Fitness on single arm shoulder press
Dr. Mike Israetel on training the front delts
Tristyn Lee doing dumbbell shoulder presses

Overhead Press

Weighttraining.guide barbell overhead press

Jeremy Ethier on common mistakes

Behind-the-Neck Press

This can be a risky exercise - only do it if your shoulder mobility is good. Try with little or no weight (PVC pipe or broomstick) first.

Weighttraining.guide on behind the neck press
T-nation.com on the behind the neck press

Lateral Raise

Weighttraining.guide lateral raise
Moji Oluwa on the lateral raise
Erin Stern on the lateral raise
Seth Feroce on angles