Yeah take belt off and try again, have a good look around the front of the engine, sounds like metal on metal. Could be a loose bracket hitting a pulley, the heat shield on the turbo...
When the engine is cold ...
Take the snake belt off (as everyone said)
There is a tensioner at the top (can be seen in in the early part of your video.. I think it's a 14mm sockeet you need and a long bar to lifyt the pulley up and release the tension.
Take a good look at how the belt is routed first ...
Check each pulley and see if you can spin then without any noises.
You can run the engine (from cold) for about 3 to 5 mins. The water pump isn't being driven so don't ket it get too hot.