How good is a totally vertical down draft port??

In this, Episode 29 of powerTec 10, DV investigats the importance of the ports CD (discharge co-effficient) or, to put it into plain language, the ports flow effciency. For this he made a port that came down vertically on the back of the valve - no bends just a straight port and valve. How efficient was it - try guessing. Chances are you are wrong!