Stumbled into this shop completely by chance while exploring Berlin, they have a good selection of experimental DVD's/ Videos + reasonable prices. Found many treasures in this shop, actually some stuff I had been seeking for a long time previously.
They have a web site where you can order stuff and practice your German at the same time. http://www.videodrom.com/
+ worth inquiring if looking for something specific, saw some stuff on the shelves which does not appear to be listed online.