Movie shops are easy and kind of fun, but generally don't pay much. Trailer checks are very simple. You watch and record the upcoming trailers that are shown before the movie and write down the audience's reaction to each, positive, negative or neutral. The MSC gives you a letter to show a manager which gains you admission to the theater. The rules state you can't stay and watch the movie after you do the check, but nobody is likely to come and drag you out of the theater. Usually you have to check all screens showing the movie you're assigned, and that could obviously be as few as one to as many as four or more, depending on how popular the movie is. There are different kinds of checks where you have to check every showing of a film on the opening day, but those are a pain in the butt unless you just have an entire day to kill.
Once you've bid on and been accepted for one of these jobs, for Market Force Purple say, they send you complete instructions on how to do it. Bottom line: Very easy assignment and form, fun, pays peanuts. But I do them from time to time because I love movies.