Hello Dan,
I have often wondered about the adjustable hemmer. I think it was intended for use on household linens rather than on more lightweight fabrics. I seem to recollect reading an old book or manual where it was suggested that it is ideal for hemming tablecloths. Certainly with dress weight cotton poplins it is probably just as easy to iron the hem into place and start sewing - and use the underbraider if you want to make it pretty... Perhaps I should try it out
So glad you enjoy the videos!