RE: How fast?
Use the formulae Speed = distance/time. Measure the distance between the two points, time it and then break out the calculator. e.g. 200 metres in 5 seconds gives you 40m/s. Multiply that by 3.6 to convert to km/h and you get 144 km/h (89mph). For over there this would be 656 feet/5 sec = 131 ft/s multiply by .68 gives you 89 mph.
cheers