Hi Ken, in this one whitecaps are much less noticeable: http://www.youtube.com/watch?v=ugBXkpfHw7o&NR=1
Another factor that may play a role is sunlight. Sometimes you see plenty of whitecaps, then there is a cloud coming and all of a sudden you see much less. (Of course whitecaps are still there, but if this can trick your eyes, it will more surely trick photos or videos). Anyway I remember sunny days with strong offshore wind, certainly more than 10 Knts, and no whitecaps even 100 meters away from the beach. Could very well be that the necessary fetch for 10 Knts to blow whitecaps is several hundred meters, as Carlosgp5 suggests. Anyone with some model?