Look like this guy is modifying his NSX for a Dirt Trials - N1 Class in Japan.
This is his Blog.
http://blogs.yahoo.co.jp/jpn11905/59458190.html
The Youtube footage is from Gunma prefecture.
Here is some from Saitama dirt track.
http://www.youtube.com/watch?v=aAbDFJnN4hU&feature=player_embedded
I give him props for trying entering it for dirt trials! I'd never do that but I'm sure it gets a lot of attention on the track!