I liked the film-maker even more than any of the artists. he is such a cool and funny guy.I live in London (until the end of the month, when I move to Malta: http://andreasmoser.wordpress.com/2011/11/13/leaving-london-moving-to-malta/) and I see a lot of graffiti and high-quality street art. Fascinating! There are some areas in London like Shoreditch and Brick Lane that you can visit every two months or so and you will find completely different pieces of art again.
Yes, french man is a funny guy indeed. Thanks for the tips, next time I go to London I'll check those places.