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A couple of things first - while cleaner shrimp do clean some parasites from fish, they won't actually control a disease outbreak. Also, if this fish has a contagious disease, moving it to the 40 gallon won't help the other exposed fish - they would need to be treated as well.
In the video, the fish is moving very fast, so it is tough to get a good view. It doesn't have velvet - that causes rapid breathing and not eating, almost from day one. If you can see distinct white pinhead spots, then it likely has ich. If the fish scratches a lot on various surfaces, it is likely to have flukes.
I know getting good photos/videos is tough, but we really need that for a proper diagnosis. If you can't do that, I recently posted a short article on self-diagnosis of diseases:
https://www.reef2reef.com/threads/self-diagnosis-of-common-marine-fish-diseases.1141555/
If I had to guess (and I don't like to do that) I'd say the fish has flukes. That is one disease that can be treated with the fish and invertebrates in place using praziquantel:
https://www.reef2reef.com/threads/dosing-praziquantel-pzq.1105700/