I watched the video. I didn’t see uproarious laughter from anyone but I think the person recording the video likely was the leaker. It’s kind of subjective interpretation but I didn’t hear them making any noises and they seemed to be keen on catching the factual aspects of the incident.
There’s only a lawsuit because the video got leaked. As for any investigation, it seems unlikely this will go past the level of a perfunctory internal review culminating in a pat on the back and a “yah done good” from IA.