It's not a video, but it is a classic thread explaining about intercepting (not 4-bearing hydrophone method). I'm not familiar with any videos showing this step.
http://www.subsim.com/radioroom/showthread.php?t=88961
Here is an image that explains it in condensed steps:
Dantenoc did make the following SH3 tutorials, videos showing how to attack a target, but only from the point where he got near the target and started plotting it's position. Not how he developed the intercept triangle drawing.