You can do it w. any camera. Just use the high shutter speed. This water is relatively slow so even 1/1000 will do. I'll post few new shots but take a look at my balloon photos. Those were shot at 1/8000 F5.6 640 ASA and an auto flash. Canon 5D has a high speed setting for it's flashes so you aren't limited by 1/125th any more. But my shutter didn't have to be so fast. Duration of Canon 580 at 1/128 is 1/30,000 of a second. When flash output's changed, it's not actually the power that's changing but it's duration.
thanks, leylena. what kind of high-speed camera are they using? is it possible to make such shot with a D700, D3 or Mark?
I think they use high-speed camera Look at High Speed Photography http://www.flickr.com/groups/highspeed/.
Especially interesting Discovery Channel's new series Time WarpM by MIT scientist and teacher Jeff Lieberman and digital-imaging expert Matt Kearney http://dsc.discovery.com/tv/time-warp/about/time-warp.html