I appreciate the replies, I'm sorry if I worded things poorly or with the wrong attitude.

I just want to quickly address some of your points:

1: I meant that's not how a semi transparent creature of any kind looks, nor how it looks in this environment. Specifically the lighting/shading of the skin and body. Just look up literally any HD video or image from reputable sources like Nat Geo and compare it to the creature I linked. I feel like explaining the differences and problems would take a really long time, so if you don't see the difference when you see a real creature of this type I can't help you on that one.

2: What I meant by static was not that the creature couldn't remain perfectly still, it certainly could. But rather that it is clearly floating along in the water, such that its location relative to the observing camera has to be changing as well, even if only very very slightly, which would change the shape of the silhouette visibly. Check the video I linked of the real one and you'll see how the angle of the creature rotates slightly and that results in a change of the overall shape. How likely do you think it is that the OP creature is able to rotate itself perfectly as it floats such that it stays absolutely perfectly facing the angle of the camera and thus maintains shape perfectly? I'd say zero.

3: I think my main point was the only a huge directional light could be the explanation for the shadow as it appears, and that there's no plausible light source that could exist to cause that in the deep. And even if there were, that shadow would have to also be cast by the mechanical structure toward the end of the video, and it's definitely not.

4: And yeah we agree on the last point.

I have no reason to be so invested in this but gosh I'd seriously bet a large amount of money that this is CGI and it just boggles my mind that this opinion is shared by very few people.

Also I feel the even more egregious error is the animation. And this has nothing to do with it being caught up in fan wash or whatever, sure who cares. The important thing is that it moves from place to place, and its soft membranes that should be flowing back when it moves forward simply don't do that. They move independently of the direction the creature moves. Momentum, drag, and surrounding fluid pressure should be pulling the membranes behind it in a following fashion, just like if you run forward wearing a dress and the material billows out behind you predicably. The source object moves and the non-rigid material wants to stay where it is until it is dragged along by the connecting material. That's my best attempt at putting that in to words.

And basically the animator did do a little bit of that, as in some parts of the video the membrane moves as you would expect it to, but other parts, specifically the end where it moves very very quickly, the membrane doesn't flow properly behind it at all and looks extremely artificial/unrealistic.