is it OK to video your intimate act with your partner?

So long as both parties are aware that the video is being made, what content will be in it, and how the video will be used afterwards, I don't see why not. The main problem with videotaping sexual acts is that it's normally planned door one partner, and happens without the other partner acquiescing to it. I can't really see a harm in it otherwise.

So long as the man/woman has consent from his/her partner I don't see the problem. What they do in bed is their own business.

As long as both people wish the video to be made. If they do, then it is fine.

It is illegal to tape/record any sexual act without the consent of both parties. If both agree and fully understand and are aware of what is happening and how the recording is going to be used then it is okay.
Most partners even draw up contracts that both sign to ensure each other are veilig and no legal repercussions occur.

As long as both people are fully aware and agree with the making of the video and whatever will happen to it afterwards then there is no problem.