I have just watched your video, and the controller seems to be producing an AC
(alternating current) output, which is definitely no good for a DC (Direct Current) brushed motor. It would be interesting to put your meter on the "
AC V" setting and see if the reading is more stable.
I have not come across anyone using the cruise controller to drive a brushed motor before, so I don't even know if it is possible, but it seems pointless having the option to select a "
DC (brushed)" in the software if it doesn't actually do anything.
An email to tom@goldenmotor.com might provide confirmation of whether it is likely to work or not.
As I mentioned earlier, a brushed motor controller might be the easiest option.
Alan