I think Rumple was bluffing about the tape to Hook. A tape can’t be found if it doesn’t exist!
I’d be quite annoyed if other characters started acting all high and mighty in regards to Zelena’s death. They didn’t care about her, they haven’t missed her so why should they get all worked up about it? She treated Rumple like crap and it came back to bite her. Emma and Snowing planned to murder Pan when he was powerless so why should Rumple actually carrying through on his threat to kill Zelena be treated as if it was the most heinous crime in the world?
I doubt the tape won’t come back up again, since it’s a vital piece of Rumple’s backmail against Hook. Also, Belle would be annoyed in regards to Zelena’s death, because she made Rumple promise not to kill her. Regina would also not be happy, because she honestly wanted to give her sister a second chance, and Rumple took that away from her. There’s a difference between killing someone in self defense, while they threaten to kill everyone, and killing someone when they are already defeated and vulnerable. Zelena was powerless and no longer a threat, so she did not need to die. Rumple didn’t kill her for the defense of the town either. He killed her in the name of vengeance.