Valleycats.net seems to be out of business. It sat on the uncomfortable verge between fantasy and competitive fighting, it had poor site design, and insisted on selling its fights in short segments.
I very rarely buy fights with punching and kicking, being far more interested in seeing close contact wrestling, and yet one preview clip caught my attention for its intensity, mutual aggression, trash-talk, and groaning. It gets pretty violent in the second half, when they're in shorts:
I should have seen the site's demise coming, since the its own billing service denied its existence when I tried to buy a download. Too bad I'll never be able to watch it in full.
The second one requires free registration. The people on both boards are posting B-movie catfight clips, using the Mediafire file uploading system. As opposed to Youtube, their clips seem to remain online. There are hundreds of them.
I found the Valleycats clip on a related board that seems to be devoted to street fights ripped from Youtube: http://www.runboard.com/btherealdeal