I could go on about defunding the Police like some places intend to do but this time I was lead to this guy making his own tape demagnetizer. Why do people of such rudimentary knowledge try to make out that he know something when they clearly show that they are surely lacking.
You should do all degaussing as it is really called with any deck turned off otherwise you will blow out the head preamps. How do I know this? I have had to fix the units that people did this to over the years and they know afterwards that they made a mistake NOT reading the instructions. Now this guy does it on his video- that little amount of magnetism from that screw will do nothing for you as it is too weak not to mention the whole idea of demagnetizing a head is unnecessary anyway. Have you ever measured the residual magnetism at a head before and after using a real degausser? If so you will find out that the reading is the same as I found out.
The fact is if someone is telling you to do something on You Tube you can guess with pretty good certainty that it is wrong- that much is true as I have watched too many of these experts call the items by the wrong terms, do things that are completely wrong. I should know.