Squaring fabric has a bit different definition in quilting vs. garment construction. When making a garment, you need to spend a lot of time getting the fabric trued up so that it will drape correctly. With quilting, you want to get it close, but it doesn't need to be as exact. Holding the fabric piece with selvedges together along the top and looking at how evenly it hangs is the standard method, as described in the video. I prefer not to make the second fold, so I work with a 22" length.