Observe: I am saying nothing

Just now I watched a little youtube.com video that explained the two slit experiment. Basically, what happends is that a pattern emerges if you use waves and another when you use particles. Then you fire electrons in the thing, and wave patterns emerge, even if you fire one electron at a time, therefore the single electron is interfering with itself! But even stranger, when you put an observer to see what slit the electron goes through, the pattern changes into a particle pattern. This proves that observation changes what we observe.

Wait a minute! But isn't science supposed to be based on observation? This very experiment has been observed, for crying out loud. So what does it mean? If you demonstrate something by scientific experimentation, therefore using observation, doesn't that mean you only demonstrate what happends when you look at something, rather than what that something is? Since the same experiment has been observed using eyes and it behaved differently when they use a finer tool, then it means the type of observer alters the result. Would things start behaving differently if an alien was to come on Earth? This is mind boggling.

Links:
YouTube video -< it was removed from YouTube
Another YouTube video
Wikipedia on the double slit experiment
Cool java applet on wave interference