Is there any other upside to this besides novelty and amusement? It's easy to imagine a dozen applications where this would threaten human privacy and safety.
* Automated injury detection. You've got a warehouse, you've got cameras, now you've got an instant alert when one of your workers appears to be injured but out of sight of other workers. You've got street cameras, now you've got automatic detection of someone having a heart attack and laying down on a sidewalk. (Dystopian application: "homeless person detected, deploying zap-drones") Hospitals and old folks' homes could use this, too.
* Lifeguard Assist programs - automatic detection of drowning-like behaviors. (Of course, over-reliance on this would be bad...)
* Children separated from parents might be easier to detect in places like malls, etc. (I'm going to stop listing obvious parenthetical dystopian applications)
I’ve been eyeing things like the Kinect and iPhone X face tracking for this kind of task (for a fun side project I’m working on), but it would be great if I could track at least position and pose of multiple actors in a scene using just a standard webcam or camcorder.
Technology is inherently usable both for good and evil. You get both by default. It takes active countermeasures - usually non-tech, like regulations - to limit evil applications without sacrificing the good ones. As a society, we do that to some extent, but unfortunately we're not as successful as I'd like (e.g. if it were up to me, I'd seriously curtail the advertising industry).
I don't think it's right to just shrug and say "everything can be used for good or bad". The details matter. If you're talking about a Yo-yo, yeah, you can hit people with it or just amuse yourself; nothing catastrophic is likely to happen. This tech though has greater implications.