That is what we call a OVA. Original Video Animation. (or OAV. Either way works)
You can find this OVA along with the one that came out a year before that at the NC site;
These videos are in rmvb format. The one you want to watch, the Waterfall episode; is Jumpfesta 2004.
You can download realplayer if you don't have it at www.real.com
If you have any further questions just PM me.