Nice clip, I think I know that branch!
If you swim to where that platform was in the lake, not sure it it is still there, look at about 30degress left when standing on the main snorkelers platform. Over in that little area there is like a mini version of Blue corner but for Jellies. Mixed with a razor sharp shadow line caused by the growth on the little penninsula that sticks out. That is where we placed a RED One fitted with an Arri 8R Ultra Prime
inside an AquaVideo Housing and basically let it roll to fill a 360Gb HDD. We set the system in place for the early morning 'ascension' of Jellies from the depths. The footage was used in the Great Migrations series by Nat Geo.
We also shot topside timelapse and hung a gantry out from a tree far away from the madding crowds and got some stellar 10hr sequences of following the jellies across the surface of the lake, fortunately the days were sunny, hot and just a few mozzies (yeah right).
Whilst we'd heard about the possibility of Salties in the region we never saw hide nor hair of one and we were in the water on rebreathers for the majority of the ten days we were camping on the location. The executive producer was sleeping almost in the mangroves and always had a sound nights kip.