The skateboard fail video is a reference to the Nickelodeon original movie, Jinxed.
"Somewhere over the Dwayne Bowe" (the name of Homer's fantasy football team) refers to Dwayne Bowe, who is a current player in the National Football League (NFL).
The "Tired comedy reference" Selma mentions, when Bumblebee Man says "Mas cowbell", is from a famous skit on Saturday Night Live, featuring Christopher Walken instructing a fictional Blue Öyster Cult in the studio recording "(Don't Fear) The Reaper".
All Bart had to do to watch the trailer for Project: After Party which was rated R, was enter his date of birth however the trailer was red card and to view a red card trailer you have to pass an age verification test which entails users aged 17 or over to match their names, birthdays and ZIP codes to public records on file. This could have been a repost on a pornographic website, which does not implement such measures.
Project: After Party was rated R but the content shown in the trailer would require an NC-17 rating.