There are two ways of watching "Batkid Begins," and both are equally rewarding. You can watch it as a heartwarming document of the time when a hard-boiled city stopped everything to make a little guy's wish come true. Or you can look at is as a cautionary tale about how, even with the best intentions, a good idea can get too big and defeat its initial purpose. Director Dana Nachman includes enough information to support either interpretation, and even to allow the viewer to shift points of view, back and forth, as the movie goes along.