the binding is one of last steps ,you sandwich your quilt and quilt it or tie it which ever you like then you can start adding binding before triming away three layers or cut the layers to edge of quilt top ,batting and backing ,but in this video notice how it,s already trimed and she pining binding then she leaves corner,s 1/4 " away from starting and ending each corner ,after she sew on binding on all four sides ,that when she finishes the corner with the binding tool sews each corner she checks frist before cutting corners about 1/4 from each binding ends