
Quoting
Taxing Matters
What the guy did does violate the federal laws regarding child pornography. Simply knowingly receiving the video of a naked 14 year-old is enough to make him guilty. So as a previous response indicated, the OP may report this to the FBI. If he gets contacted by the FBI before he posts anything online then he'd be real fool to compound his legal problems by posting it, which would constitute a separate and more serious offense. So that may help provide an avenue to prevent the posting of the photos.
In addition, the OP could seek an injunction to prevent the guy from distributing the video to anyone.
So I think there are things the OP can do before he posts the videos, and it may well be worth doing to ensure that the videos are never posted.