Wrenching video showing a 91-year-old Long Island woman mouthing she wants to live amid a pull-the-plug court battle suggests she was being coached at the time, a court evaluator said Monday.

As The Post exclusively reported Sunday, Edward Lester filmed his bedridden former school-teacher mom Arline hooked up to a ventilator at Mount Sinai Medical Center in November mouthing, “I want to live” and, “I want to stay alive.”

Edward says the footage helps proves that his mom should be kept alive, despite claims by his younger brother, Kyle, that to do so would be going against her wishes, as outlined in her 1999 living will.

But a lawyer who was appointed by a Nassau County judge to act as a neutral investigator for her in the case said Monday that it looks like Arline was being coached in the footage. The video includes Edward first saying a sentence, then asking, “Right?” and urging his mother either to repeat what he said or agree with him.

Edward’s lawyer, Jonathan Rosenberg, protested to the judge, “That is a very inflammatory comment to say words were put into her mouth.”

But the evaluator, James Murphy, shot back that the Edward “did instruct [Arline] to mouth certain words.”

Both Murphy and Arline’s court-appointed lawyer eventually urged the judge to seal the case for the sake of her privacy, which the judge agreed to. A gag order also was slapped on all parties, preventing them from commenting further.

Kyle Lester is seeking to be made the sole guardian of the brothers’ mother and has already indicated that he wants her taken off life support because that’s what she has said she would want.

Edward says his mom signed a new living will in November indicating differently and is fighting his brother’s legal move.