I looked at your video, and it looks to me like your fish has ich. Ich is very deadly and extremely contagious. You may want to treat the tank with "Ich Attack," "CopperAid," or other Ich medications. Treat ASAP. Also, while your fish has ich, they are very stressed and vulnerable, making them an easy target for bacterial infections. You may also consider treating the tank with a medicine that provides a temporary synthetic slime coat, which will: (a) help fight injury/infection, (b) protects them, (c) keep their stress level down and reduce vulnerability. Also, API Melafix can/will treat any bacterial infections the fish may have or could soon get.
I hope this helped you and your fish, and feel free to let me know if I can help you in any other way!
Lauren Pauly