Filmmaker James Marsh understands that any old documentary on a high-wire walker might be dull, and any new one on the World Trade Center might be dreary. So how about a high-wire walker at the World Trade Center? History has only one such person: the grandly mischievous Philippe Petit, who worked his way up from the Notre Dame Cathedral to the Sydney Harbor Bridge to those famous-making 45 minutes between the Twin Towers in 1974. It took months’ worth of recon and a team of drolly goofy accomplices — united, as one of them puts it, to do something “against the law but not wicked or mean. It was wonderful!” Retrospectively rooting for these creative criminal infiltrators is all the more moving because Marsh never mentions September 11. With a title borrowed from the “details of complaint” section of its protagonist’s police report, Man on Wire is a marvel of discreet affirmation.