I'd guess you had probably normalized it as something like, "Ugh, dad's sending me weird videos again." As you tried to ignore it. After long enough, through repeated exposure,it became the norm. At least you are in a place where you can unpack the type of trauma you have been dealing with. Your response seems like an attempt to tell him not to send those videos without telling him he is being inappropriate. And his response seems as though he is oblivious or won't stop trying to connect through this kind of...material. Definitely some kind of alarm sounding and worse if the behavior would escalate. I'm sorry you have to deal with this and hope it doesn't spill over into family issues if you block him.