Learning to bunny hop on a MTB
The trick is to remember how pedals are designed to grip.  Decent pedals should grip your foot from going forwards or backwards, as well as obviously holding your weight.  The only direction they don't grip is upwards away from the pedal.  The trick is to rotate the pedal so that it's allows you to grip in the direction you want.  You rotate your feet towards 45 degrees and you will be able to actually grip your pedals to pull up the back end of the bike.  

Keep in mind how the pedals grip and you shouldn't go far wrong.  Assuming you've dipped the front of your foot the action you need is effectively pushing backwards and upwards at the same time to lift your rear wheel.  Don't dip it so much that you end up going off the front of the pedal though.  The backwards push should keep you gripped on the pedal while the upwards action lifts the wheel.

As you said, there are plenty of videos out there.  This one explains it in a way that roughly matches how I figured out how to do it.  The relevant part is about 2:10 in.

http://www.guardian.co.uk/environment/bike-blog/video/2011/feb/21/danny-macaskill-video