V1.3 update: Used higher quality videos and trained at a higher resolution.
The main part of the prompt is:
A woman is straddling a man and having sex with him. She bounces up and down on top of the man
Depending on the angle of the camera, you can either directly see the genitals or not. You can add this to your prompt to try to get them to show up:
You can see the woman bouncing up and down on the man's erect penis.
You can prompt for different angles:
{The view is from the front and at a 45 degree angle|The view is from the side|The view is from behind at a 45 degree angle|The view is POV}
By default, the woman's knees will probably be pointed down, so if you want more of a squatting position with her knees up, you can prompt for that this way:
She is squatting with her knees raised Civitai