You have three options that I can see.
Firstly, you do nothing and hope that this group doesn't consider the video to be interesting or incriminating enough to post on the site. I don't know if they know you're real name, I hope not. If they don't and the video doesn't clearly show your face then you won't garner much attention even if the video is posted. If your face is clear on the video then they can probably find out who you are by searching the web. So a good idea for now might be do delete all the pictures of your face that you can from your various accounts, and either temporarily or totally deactivate them or restrict who can see them to you only.
Secondly, you could contact the group and plead your innocence and remind them that they'll be destroying a career and life and family if they do post the video. I hope that they don't have more than one video of you, and that you don't have a history or criminal record for this sort of thing.
Thirdly, go see a civil lawyer. Have that lawyer write them a letter threatening court action, including an injunction against them and defamation action with damages and legal costs, if they do post it and you want their commitment to delete the video without any dissemination. The lawyer will know what to do. These guys are skirting the law themselves and I doubt that they'll want the cost or annoyance of a court case against them at this point. Of course, if they call you're bluff and post the video because they want media attention from a lawsuit against them, you have some harder choices to make.
Those are my best recommendations. Choose well, or go see a lawyer in person and see what they think right away.
Anything else to discuss? I'm here if you want to comment or reply. If I've answered you fully I'd appreciate a positive service rating please.