You may find interesting this post: http://www.v13.gr/blog/?p=44. It is a way to do the experiment yourself, just like I did after I looked at your double-slit videos, without using specialized equipment. In fact, you'll be able to see live the effect of lighting/darkening the second slit. The live result is really amazing.
I'm not a physicist but I believe that the results actually show the interference pattern (but please, correct me if I'm wrong).