I have just started no contact with a narcissist, but I'm scared that he will blackmail me with images that he forced me to take.

If he forced you to take these videos, have you contacted the police?

Black mail is illegal, so is extortion, and if he forced you into anything the police should have been called.

Of course unless he held a gun to you, he did not "force" you, and once taken, photos and videos are subject to be shared. So just assume some of them are already out and go on with life.

But do no contact, if you do not read his email, do not answer his phone calls, do not read any text message, you will not know what he is threatening or saying. So he will have no power over you, if you do not even talk to him again

I agree - how does someone force you without a gun to your head?
And how will the pictures be blackmail material? Do they show you doing something illegal, or are they just nudity and sex, which in this day and age is pretty weak blackmail.