Through a combination of tactics and luck, Boston has so far avoided eruptions between its police officers and communities of color similar to those that have roiled such cities as Ferguson, Mo., Baltimore, and Baton Rouge, La., in recent years. That’s why it’s so important that the Boston Police Department conduct a thorough investigation of a questionable video featuring one of its patrolmen.

A spoof of a cop buddy-comedy movie trailer, the brief clip shows photos and captions of the officer and a canine in a leg cast — described as “an inept cop and a dog with a limp” — who team up “in the fight between good and evil.” Near the end, several photos of African-Americans are shown with the words, “This summer, black people have met their match.”