That's not what I am saying.
If/when one of my gangsta teenagers gets caught waving drug dealing videos around, hopefully they are not so dumb to have any identifying features, but say their underage tattoos were on show, and they got caught or grassed, me and their father would sort them out, however was needed. I can't say if that would be tough love or a more compassionate approach because it hasn't happened yet.
It would be tough love if I had to explain to the police that their dumb arses were only pretending to have weed and it was all a big hoax.
I would expect the friend's parent to contact me directly first. Even if just to tell me they were going to the police so we could work out what we were dealing with.
But OP doesn't say they are friends.
This is a 12 yr old who saw a video, that may or may not be true, of another 12 year old, who may or may not be affiliated with a gang of older members.
If you as a parent open up a can of police and social services and the 12 year old is part of a gang, some of whom might carry knives out of school, or even in school, I would say as a parent you need to be sure that you don't embroil your child with them. And on what information that has been given in the OP I don't think I would say anything right now.
I would talk to my 12 year old, to keep their eyes ears open. I would suggest my 12 year old talks to his trusted mates, but I wouldn't jump in just going on this information. I would tell my son's friend's parents to make sure they spoke to their kids or just to make it aware that there MIGHT be weed floating round sometime soon.
I wouldn't just do nothing but I would tread carefully especially as my child has asked me not to say anything to the authorities.