I have had days with almost zero whitecaps at Mentor Headlands beach on Lake Erie. The fact of the matter is that there was a very short fetch. There is this phenomenon when the water is still very cold and its a warm sunny day, the wind right near this beach picks up VERY steady, and just near the beach. You can see a reverse wind line about a mile out, where the water goes from light ripples to glassy. There are no whitecaps because the wind hasn't had time to get the waves moving. But I had some really great sessions that way. I learned to do aerial rotations on one of those days.
And I agree, the video isn't a good comparison. SUP vs. raceboard. But it does argue very well for the Crossbow.
How about the Skingshot Turbine? Anyone have any experience with that as a light wind kite?