what I think I saw was a second row passenger on the left side of one of the helicopters seeing the other helicopter getting closer from the left and below, and repeatedly tapping the pilot on the shoulder to bring the pilot’s attention to something the pilot wasn’t looking at.
The in chopper footage which covers the 12-13 seconds from when the departing helicopter departs overhead the pad to impact has the left hand second row passenger just filming with his phone. He seems oblivious to the approaching chopper. The centre (?) pax is the one who sees the danger, and taps the pilot (vigorously I'll admit...as you would) immediately before impact. He basically taps the pilot and then grips the seat back in anticipation of the collision. What we can't hear is the audio. I'd imagine from his arm movements he's saying something and the pilot is not reacting. The shoulder tap is in desperation.
Two helicopters collide - Gold Coast, Queensland - Sea World 2/1/2023 - Page 9 - PPRuNe Forums post #171
I doubt in the traffic scenario around Gold Coast scenics that any ADSB info was going to be taken notice of.