Go Swim is by far the best resource for high quality video of EVERYTHING swim related that I have found. I learned about it when I was a member of our local Master's swim team.
Here is an example of one of the videos:
Basic Flip Turn Video
Some of my favorites are the Drills videos, which break down portions of whatever it is you need help on. Like this one for
Flip Turns.
Those are the most useful to me these days, since I can't swim with the Master's anymore.
Happy swimming!