Many "mainstream" sexually explicit videos target a male, heterosexual audience and

1. portray dominant men with huge erect penises
2. show men ejaculating on women's bodies
3. portray the image that men must "last long" to satisfy acquiescent women.

They portray all of the mentioned.

Explanation:

People who make mainstream sexually explicit videos target males, heterosexual and tries to portray a lot of things in these videos. One thing peculiar with these videos is that they are known to always show men having huge erect penises ready to achieve penetration. They are also known for showing men who would rather ejaculate on the bodies of the female. One thing that is also very easy to see is that men in these videos last so long in the sex act; reason being to guarantee satisfaction from the acquiescent woman.