Below is a really interesting, somewhat quirky British documentary on the sewing machine I found on Youtube. It explains and shows how a basic machine works, tells the shocking life of Isaac Singer and show how machines make fancy stitches. Don't miss the how they demonstrate the workings of a sewing machine with the "human sewing machine" and the Monty Python like animations.
It is in three 9 minute segments. Hope you find it as interesting I have.