Question about custom brushes and paths

Hey all-

I swear I’ve seen a demonstration where someone had an inventory of custom brushes that when applied to a stroke made by the brush or pencil tool, would follow the stroke.

I don’t think this was the same as the symbol library because he was able to take and image (in this case a basic photo of an arm), and apply it to a path made by a stroke, thereby making the image of the arm move in the same pattern as the stroke.

Does anyone know what I’m talking about and how to do it? I have a specific stroke image that I’m looking to use, but I want to know if I can manipulate it along a large variety of paths. Any input would be most welcome.

bloaty