I watched the video but it was only 32 seconds long. You referred to a location at 58 seconds though...?
From the 32 second video that you posted, I didn't see anything drastically wrong. Now that he's in warm, clean water and getting good food, then any fin issues should start to heal.
If you want to add something, maybe look into API Stress Coat. It contains aloe, which can be soothing, and can help promote healing.
But I think that you're giving him a good home now, so he may just need some time to heal up.