Yeah, looks like the “yellow oxygen tank” is a gymshoe sole, and the “black wetsuit” is just someone’s wet, black pants as they break the water.
The hilarious part of this latest conspiracy theory is that, just a few seconds before this “diver” appears, the video shows an underwater shot, from an angle that would have shown any diver hiding underwater, but nobody is there. The evidence debunking the theory completely is right there in the video, but you’ll only notice it if you are not searching for evidence of a conspiracy with a closed mind.
You know, I love a good story, however I think you are correct, it appears to be a shoe and pant leg, as a former search & recovery diver for the FD I have an idea what to look for as far as diving gear goes.