It's a Finnish Merc that, the video was shot in Latvia though.
There's apparrently a whole subculture here based around these tuned old diesel warhorses. They call 'em Super Turbo Diesels. Most are based on 300d engine as the block on 'em is quite bulletproof and can handle huge power with relatively small changes. The scene seems to concentrate on mechanical changes rather than cosmetical ones. Most of these cars look quite rude, but pack around 400-500 horses and silly amounts of torque.
There are some nicer ones too. This one in particular: