How long does it take a cat bite to heal? Will my cat attack again?

The video did frighten him. It wasn't that he was trying to bite you but lashed out at the first thing he saw, that being you. A red mark creeping up your arm indicates blood poisoning which needs to be treated promptly. If you see it getting worse then you must go back to the doctor. I don't think your cat will strike again. This is usually something that doesn't repeat itself. Oh, and don't play the video.