this guy does a pretty good job on his sniper 101 series. Kind of redundant and rambles some, but stays on topic pretty well. He has a pretty nonconventional approach to shooting in a lot of respects. I think he has 2 videos on angle of fire corrections.
He discusses using a cheap plastic protractor and determining your own corrections rather than having a rangefinder calculate it for you. If you remember your trig from high school, it's relatively simple.