Rook + pawn vs Rook endgames

Hi everyone
I have some issues with Rook + pawn vs Rook endgames, today even couldnt win with 2 pawns advantage:
http://en.lichess.org/QTq0OpOiy582
-.-

So I decided to watch some videos to get some general ideas (where should the rook and king be, where shouldnt be, when to move pawn etc).
I watched this one:
www.youtube.com/watch?v=xe75EPT6pig
but still dont get it how black can achieve draw at 6:55

Tried it with stockfish, but Lichess one also dont know how to draw this -.-
http://en.lichess.org/kJ93MOuiz8vD

Or maybe it isnt a draw?

Any other usefull resources about this type of position?

The position you set up is backwards. Basically, it's a draw if the side with the pawn has his rook in front of the pawn (on the promotion square).

Holy duck. My mistake.