I would bump that temp down, if you could. Go another point for today. He's breathing hard in that video, that's why it looks "odd" in the picture.
Evidently, it's something infectious/transmittable and more than likely started by the new guy, but not necessarily.
I'm not an expert, I've just been around them a long time and had some really cool experiences. Besides having all the different pipes as pets, I used to bring home tonnes of them accidently when I went collecting grass shrimp in Texas. I'm one of the mods over on Seahorse.org, but as you can see, that site has died and I don't even go there myself anymore. It used to be so crazy active and we had a pathologist onboard who would do necropsies on horses from the threads. So, we had this beautiful thread of details going up to the death and then an awesome necropsy report. My bestie is Fusedjaw and her stuff is impeccable. So goes to a lot of conferences of them, so she's more up-to-date than I am. My husband and I met on Seahorse.org, so you can imagine that we were as involved as one could be. One of the other mods started his own breeding business at Seahorsesource.com and it was cool to grow with him. Anyways... my point was I'm not an expert, but evidently I like to talk a lot. LOL!