The seller is wrong. In any case, if the heater would have over heated you would have noticed as the machine would have burned wires which you would have smelled and noticed, as the motor would not have turned any more.
In any case it is absolutely safe to run a CPE2 with the temp dial down all the way (you can hear the thermostat clicking on and of when you turn the dial, the point will change with ambient temp, but as long as it is beyond the position in which it clicks off, it is OFF...).

From your video, it seems as though the reversal arm (three fingered white plastic bit) is out of position. As far as i can see the drum revered direction as soon as you manually moved the reverse arm and clicked the micro switch.

This is very easy to remedy - the first thing to check is to tighten the screw of the revereser, so that it takes a bit more then light finger pressure to move (do not over tighten so it does not move at all). Then re position it with the middle prong level\horizintal, and run the motor, this should cure your problem. You might need to start with one of the other two prongs level if that does not work.

If all three positions did not help after re tightening the screw you will need to re position the reverser in relation to the micro switch actuator on the inside of the unit (this takes 1-2 minutes and involves removing and installing 6 screws). But check the first step and report back. I will help further if needed.

Good luck!

Pay no attention to Ebay sellers with bad attitude, you are in the right, and in any case your machine is 100% fine