Having just played a tournament match with a big-hitting young guy, I found another use for my tennis video, and any camera will work if you know the frames per second. Namely, you can calculate the mph of any ball by first determining the point of contact when the racket first hits the ball, and then some other point of reference (i.e., the ball hits the net, that’s 60 feet) and count the number of frames that it took to get from one point to the next. Divide the number of frames by the the frame rate (which is 30 in the case of the VADO) to get the actual time elapsed, and knowing the distance, you can calculate the speed in feet per second. Google the conversion from feet per second to mph is easy, though a conversion factor of .68 times feet per second gets you close to miles per hour. In my case, my opponent was hitting first serves between 103 to 118 mph. And really, unfortunately, many of them were in the corners.
At least, that’s my story and I’m sticking to it!