Garage Door Opener Drive Belt Adjustment With 1/4 Ratchet, 1/4 inch-12 point 1/2 Inch Socket, Pliers

I neglected to state the 1/2 socket size in the video; yours might be a different size if you have a different brand or model of opener. The idea is that a socket can be used if it is small enough, it makes the adjustment of that nut much easier.
Do not over-tighten the belt; snug and not sagging is the goal here.
If you use needle nose vise-grips like I did, place them where they don't crimp anything.