I was quite amazed when I captured this shot, it was only my 4th attempt too! In movie mode, there isn't enough light for me to get a fast shutter (no flash), and hence a clear image of fast events, not to mention the unlikelyhood of it actually being there with only 30f/s. Your lucky to have got that shot yourself.
I measure the speed the same way you do Electro, I think. A microphone is placed between the nozzle and target, and the distance between the two "bang" rising edges is read off from the wave editors scale. Measurements were taken at 50cm and 1m. The range, hard to tell, but it is quite a lot despite the small wieght of the payload. I'd definately need to take it outside somewhere to find out, and then it'll be difficult to find it again. It'll reach any place indoors without any noticeable trajectory arc, thats over 7m some places.
Yeah, those professional rigs are very expensive, but the sound trigger alone isn't really.You'd need a camera that can use an external trigger though.