I think that this clip is interesting- both because it shows a professional fighter sparring with a knife (which is unusual!) with an opponent who is a classically trained martial artist (Krabbi Krabong)- and also because he talks quite openly about the experience on the blog below the clip. ("…to be honest…I thought I would do a little better then I did."!)
I'm making no judgments about the style or techniques shown- and I don't want to read too much into what was obviously just a bit of friendly sparring, but I just found it very interesting.
I trained with both of these fighters in Thailand this year- I had a private lesson 'in the cage' with Mr Elbe and it was a very intense experience- he has a very aggressive style. In contrast to Mr Gidman who has an almost Burton level of Zen calm
http://www.magicalray.com/have-you-seen-this-guy-he-stabbed-me-with-a-knife-today.html