It depends. Is the temptation extremely mild, so that there is little danger that you will actually give in to the temptation? And have you watched such things before, felt some small temptation, and easily overcome it?
Or is it strong, so that there is a great likelihood you will give in? Do you know from experience that watching such things generally causes you to sin?
If the latter is the case, this is a near occasion of sin, and must be avoided. If it is a near occasion of mortal sin, deliberately putting yourself in that near occasion is also a mortal sin.
If the the former is the case, it is probably a remote occasion of sin, and venial, not mortal. These should certainly be avoided–don’t trivialize these, trust me!–but do not constitute grave matter.
I noticed that you are part of the OCD/Scrupulosity group on this forum (so am I, actually). I would definitely caution you to talk to a trusted confessor and ask him to help you determine whether a situation truly is a near occasion or not. During my most severe periods of scrupulosity, I was convinced that many situations were near occasions of mortal sin for me, when in fact they were not sinful at all. I don’t know if this is the case for you, but while you need to make sure you *never *put yourself in a true near occasion of sin, don’t go around labeling everything as “near occasions!”
I hope this helped!
