When your neighbor is...uh...being stupid...

We're watching a drama unfold across the street. Our neighbors, none of which appear to be experienced loggers, are taking down a tall (about 60 feet tall) tree. After several attempts, a stuck chain saw, and multiple retying of the rope, the top half of this poor tree finally came down. This has been a 2 hour event, and now they're starting on the second victim, uh, tree.

At what point should a concerned neighbor step in? Should I just wait until there's blood or property damage and call the authorities? Assume it's nunamybizness? Tough call and here, I'm trying to concentrate on the market numbers for the week....

Skill or dumb luck?