If black captures the hanging pawn, that is known as the Open Variation of the Ruy Lopez. I didn't want to get too deep into theory with this video as it was only supposed to outline opening ideas. White regains the pawn back due to his pressure on the e-file.

You can read more about the variation here: http://en.wikipedia.org/wiki/Ruy_Lopez#Open_Defence:_4.Ba4_N...