I can't understand how Scott does his dipping belt here

This pic below is understandable

This pic below is also understandable

There's a hook where the red circle is.

And no hook on the other side of the belt where the green circle is

Then he continues threading it through,, and then it gets crazy.

The pic above is fine.

Then,

Somehow, the hook where the red circle is, ends up clipped onto not just the end of the belt where  it already is, but it gets hooked onto the end of the belt where the green circle is. But it seemed to happen automatically.

See the pic below

How on earth did that hook end up clipped to both ends of the belt?

Did the end of the belt where the hook wasn't,  push aganst the door like part of the hook on the other end of the belt, and so it happened automatically like that?  If so, how often does that happen? like 1/20?

@Johnny512 Lol I had never even noticed this but now that you point it out.. that is crazy. The hook must have literally opened up as I pulled the chain through.. not sure I could do that again if I tried lol.