+1 - Both OP with the missed safety announcement and the other note above about the kids in the exit row had an easy path if what they saw was something they really considered as needing action: say something then and there to the FA. If the FA blows them off, sure go ahead and report it to DL and FAA.

But, nobody likes a holier than thou snitch who just wants a couple of thousand miles. That's simply mean-spirited and serves no purpose other than getting somebody else in trouble.