This is pretty much what I do, but I use a clear ruler and a calculator.
On a serious note, his putt went too far. Although his "yancymeter" is in the correct position for drives, irons, and chips, the power meter moves to the right slightly for putts, so you have to play pretend a little: 50% on the meter is actually at 47.5% on his ruler, and 50% on the ruler actually corresponds to about 52.5% on the meter... so when he shot it "a little over 50%," he was actually shooting it 54-55%. On top of that, on a fast green, a 22 ft putt (which is a pretty accurate adjustment for the 6 inches downhill) should only be hit about 21.5 ft, which would be about 45.5% on his putter. The fact that "fast" greens make the ball go slightly further than what the power meter reads (which is why the 22 ft putt should only be hit 21-21.5 ft) is something that he will likely pick up on within a week or so.
On a less serious note, the video was hilarious... lol... and what's with all the crazy markings? Why 95% and not 90%? Why 62% and not 66.6%? ...lol... crazy man!