Both of these videos include the Thumbcuff illusion although they also include other stories, etc. The illusion is toward the end of the first video and at the beginning of the second video.
Call up and volunteer and have him lock you into the thumbcuff. Show everyone how tight they are. Then have your volunteer cover your hands with a handkerchief. In a few seconds, you’re free. Why? Because you know the key. Share with them that Jesus is the key to being set from free sin. Then lock your volunteer in. Watch him try to figure out how to get loose and then explain that he needs you to bring the key to him. In the same way, we all know people who aren’t saved. They need us to take the truth of the Gospel to them so that they too can be set free from sin.