A porn tape (referred to in My Immortal as a p-video) is apparently a means of cancelling someone in the My Immortal verse. Through most of the fanfic Snap and Lumpkin attempt to blackmail Enoby by filming her naked; this backfires spectacularly in Chapter Twenty where they inexplicably have sex in public, allowing Evony to record them. In the very last chapter Snap recovers the original porn tape and claims that Ebony will be "just like that goffik girl Paris Hillton", implying the latter used to be a goff but became a prep after the public humiliation of her porn tape being leaked.
In spite of the public reputation dangers the goffs are more than willing to record porn themselves. Vampire films Enony and Draco having sex in Chapter 28 while TaEbory films Hedwig and Voldemort going at it in Chapter 41. In both cases the porn tapes are confiscated by a third party (Snap and Dumblydork respectively) so once again this has the potential to backfire.
With the exception of the two consensual examples, all porn tapes in the fic fall under the category of revenge porn, which is illegal in most countries (though apparently not in this take on the Wizarding World; Snap is sent to Azerbaijan on other charges). Though the fact that the victim is consistently blamed/implied to be blamed may sound odd to modern sensibilities, it is distressingly true enough to the culture of the mid-2000's, which saw several actresses having damaged reputations due to leaked porn tapes.