FIRST: and this is just to get it out of the way, have you use the cheat menu to do anything, specifically, max out everyones points. as doing so could break the game.Sorry for asking this, but for some reason I'm unable trigger the event where Rebecca gets blackmailed, I already have the video? Is there something that I am missing?
Once you've recorded the video outside the classroom window
all you need to do is wait till the next day, enter the classroom, and you should get the option to show her the video or not.
I only requisite I can think of is, she should be 30 points.
if you're still having trouble, you can grab my 0.10 save from my signature and start from step 157