11:25 AM PT -- Benjamin Brafman tells TMZ ... neither he nor his firm ever met with Thompson or any of the other women named in the suit. He says if Alex Spiro met with any of the women he did so on his own time, and not while working with him. Brafman also says Spiro never met with Weinstein while at his firm and had no connection with their representation of Weinstein.

Harvey Weinstein turned a woman's sales pitch into a full-on sexual assault -- which was captured on video -- and followed it up by raping her in his hotel room ... according to an explosive new class action lawsuit.

Melissa Thompson claims she had a meeting with Weinstein at his New York office in September 2011 to pitch her tech company's new video platform to use in the movie biz, but almost immediately he started harassing her. She says there's video evidence of this because her computer's video camera was on for the pitch.

According to the suit ... Weinstein at one point reached down and began caressing her leg and moved his hand under her dress and mumbled, "It's fun when you do this." Thompson claims she ignored it and carried on, fearing he would become angry and aggressive if she rebuffed him.

Thompson says she went to a follow-up meeting with Weinstein at the Tribeca Grand Hotel later that day hoping to secure the video deal, but the meeting quickly moved to his hotel room ... where he forced himself on her. She claims she escaped and went to the bathroom, but when she came out he was naked from the waist down.

According to the suit ... Weinstein tried to force her to perform oral sex on him but she refused, so then he pushed her flat on the bed and raped her. Thompson claims he then masturbated on the bed next to her ... then acted like nothing happened once he was finished.

Thompson claims she felt "dirty and ashamed."

Flash-forward to 2017 -- Thompson says a friend encouraged her to get in touch with attorney Benjamin Brafman to take legal action against Weinstein. She says she got in touch with Alex Spiro, another attorney she claims worked for Brafman, and shared info with him about her alleged incident with Weinstein ... including the video evidence.

According to the docs ... Thompson was shocked to later discover Brafman represented Weinstein.

Thompson and 2 other women have filed the class action suit against Weinstein, Miramax and several other companies for the alleged rape and other instances of sexual misconduct. They're asking for damages.

Spiro tells us ... "I never have and I never would represent Harvey Weinstein, and, in fact, I represent one of the key victims, but Ms. Thompson has never been a client."