As others have mentioned, I don't think there is a way to totally block video access. You can always install a app, and video can be played through a web browser.
If you are worried for a child or such, then all I can suggest is getting a dumb\flip-phone. All most all smartphones are going to have the option to play video.
If you are worried for yourself, it will have to come down to a battle of willpower to avoid it, or the dumb/flip-phone option.