Earlier, someone posted a link to a video where they reproduce a fake messenger conversation with Alefantis.

Here's the thing. Above the Facebook chat box, there are a few icons. When you message someone on Facebook who isn't your friend, the video and audio icons are greyed out, because you can't video call or audio call people who aren't your friends. The icons look like they look in the "faking" video. In the "verification" video, guess what? The icons are not greyed out. For some reason, he can start a video or audio call with this guy who is not his friend (and clearly has pretty high privacy settings).

Try it out yourself. Open a chat box with a friend and a stranger on Facebook. Notice the difference.

He's edited a chat he had with a friend using the method described in the video. He's taking you for a ride. Don't fall for it.