Why middle piece of metal after ctrl +b works backwards or outwards I dont know how to call it. All rest of metal pieces went perfectly but this one fore some reason have this problem. https://youtu.be/PeZXEConG74
you might have vertices on top of each other.
Actually let me change that. I think the bevel is working but you don't have clipping enabled. try beveling and then hit C to enable clipping. Also hold down shift to control your bevel easier.
wendy10698 is right with her first idea; you have double Vertices.
You can see that, when you try to Bevel, the original band stays 'underneath' the mess.
Select all and M > Megre by Distance should fix that.
spikeyxxx When I did experiments with double Vertices I didn't get the same result as was in the video. But when I beveled w/o clipping it seemed to get similar results. That's why I changed it.
wendy10698 here's a comparison without Clamping (right with double Mesh...'original' band stays untouched):
and with Clamping, it just stops Beveling when two Edges meet:
