Double slot experiment question

Here is a video from the wacky what the bleep do you know video.

[youtube]DfPeprQ7oGc[/youtube]

Everything in the video is confirmed by reference, except for one thing at the end. They claim that observation changes the interference pattern to a non-wave pattern.

How do they know that the observation apparatus isn't just interfering with the experiment? How can they even make the observation if they're quantum particles, anyways?

I could be wrong, so don't quote me on this, but I believe I watched another video on this where it explained that it wasn't because the particles were being observed (which is a bad word as they were being measured not visually watched) but because the item used to measure the particles caused interference in the particles path. This caused them to act in a different manner.

I don't think that's true. It isn't the method of observation that causes the collapse of the wave, or the interference of the tool used to observe, it's the observation itself, which is why quantum physics is so weird (and why Feynman said nobody understood it, and Bohr said if you weren't shocked by it, you didn't understand it).

Edit: doesn't the two-slot experiment also predict the many universes theory? When the particle seems to enter both, one or none of the slots and behaves like a wave, interfering with itself, all possible outcomes have occurred. Interesting link.