Watching the videos I knew the issue was either the drum belt or the idler pulley for my dryer (Samsung, DV53J8700/EP), so I ordered both parts. The parts arrived quickly. I expected to disassemble the dryer to reach the problem area(s), but found that the vent tube could be removed. The belt was intact and the idler pulley was destroyed. I could replace the idler pulley through the bottom without removing all the components of the dryer. If I knew exactly what the problem was from the beginning (if I had done this repair before) it might have taken me 15 minutes start to finish. (As it was it took longer... :) )
All is repaired and working.