Is watching videos of people masturbating a sin? I watch just so I can know how to masturbate and nothing else.
I don't think you are being fully honest with yourself. I don't know anyone who had to learn how to masturbate, though all men have masturbated. Even if you could stretch things to claim you needed to be shown how, one time would have been sufficient, but you tell me that you have been watching multiple times and are continuing to watch them. The videos would be erotic in nature, regardless of what you tell yourself you are using them for. "For this is the will of God, your sanctification; that is, that you abstain from sexual immorality; that each of you know how to possess his own vessel in sanctification and honor, not in lustful passion, like the Gentiles who do not know God" (I Thessalonians 4:3-5). They are designed to arouse lust in the viewer; therefore, they are a form of pornography. Your argument is about as bad as someone claiming to watch pornography in order to learn how to have sex.
OK. I understand. I have refrained from watching such videos for about four months already, and I will continue doing so. I apologize for my actions. Thank you so much for your answer to my concern.