Well, this is about a game rather than a movie, but it still qualifies otherwise.
(the scene: a GameCube demo kiosk which is playing Metroid Prime inside Sam Goody. I'm watching a kid who's maybe 12 years old play the game. He's at the beginning right after Samus gets out of her ship)
Kid: What's going on? What am I supposed to do?
His younger brother: Jump off the edge there!
Kid: (runs into the force field that prevents you from plummeting off the edge) No, that doesn't work. What the hell? Why can't I do that?
(he begins shooting everything in sight and finally hits one of the six switches that you have to hit to open a barrier)
Kid: Hey, it turned red. That's probably good.
(he continues randomly shooting things until he hits another switch)
Kid: Oh, I have to hit lots of these.
(he continues to shoot randomly, not noticing that there are four other switches that look exactly like the ones he already hit. He eventually opens the barrier by shooting at random and proceeds through)
Kid: Now what?
Younger brother: (noticing the scan point) Shoot that thing!
Kid: (does that) Doesn't work. What the hell?
(while wandering randomly around, he happens to pass near the scan point)
Demo: Press left D-pad (insert picture here) to use the scan visor.
Kid: (continues to wander around randomly shooting things while these instructions are sitting in the middle of the screen) This game sucks!
Demo: Press L (insert picture here) to scan objects.
Kid: (still apparently not noticing the words in the middle of the screen) This game blows!
(he puts down the controller whereupon a nerdy Asian literary snob who happens to be nearby eagerly grabs it up
)