The father/manager of Thora Birch insisted on watching his daughter film her sex scene with Dean Winters in the movie The Winter of Frozen Dreams. I mean, he really insisted.

“It was so wrong,” said one insider. “The director is saying, ‘Harder! Faster!’ and the father is giving Winters the thumbs up.”

Jack Birch was on the set every day giving orders – even telling director Eric Mandelbaum where to place his camera so that Thora would look her best.

Mandelbaum was about to shoot the first sex scene Monday when, “all of a sudden, the front door is being kicked in. Her father was threatening to kill the assistant directors. Then he threatens to pull her from the movie with three days of shooting left.”

Making matters worse, a problem with the focus on the camera necessitated 14 takes.

“It was the most bizarre, perverse scene,” said our witness. “One girl on the crew broke down crying.”

Interestingly enough, Jack Birch met Thora Birch’s mother, Carol Connors, on the set of Deep Throat. You may remember that gem of a movie as the porno of pornos. So Thora should be used to this. I’m not saying it’s alright. What I am saying is when you reach that tender age where you can watch your mom shove someone’s pole down her throat without wanting to kill yourself, you become a little jaded.

• Dad crashes star’s sex shoot [Page Six]