There is a scientific consensus that perpetual motion in an isolated system violates either the first law of thermodynamics, the second law of thermodynamics, or both.
There is a long history of different types of failed perpetual motion machines - enough for books to be written.
Kevin Kilty has written a more readable discussion on the types of perpetual motion machine, and provides a categorisation of the types of false claims that they make.
A very quick review of the list of videos, and we are able to categorise them.
Free Energy Magnet Motor (Engine): Category 5 = Fraud
The claim is that the electromagnets in a simple electric motor were replaced by permanent magnets, requiring no external power.
It only takes primary-school science to understand this is a fake. Electric motors require the polarity of the magnetism to change as the axle turns. A permanent magnet would simple freeze the axle in place.
I speculate a hidden battery, although I also considered an electromagnet hidden behind the carpet.
Xpenzif free energy screw magnet motor: Category 6 - Perpetually Out Of Balance
This design will not work. The magnets will not pull the next screw-head forward, as it would be dragged back by the other magnet closest to a screw-head.
The video shown would be easily faked, as the base of the axle was not shown.
Steorn concept Permanent Magnet Moter Test: Category 8 - Machines without losses or friction
Only a prototype, which was not an isolated system, was shown. The device is manually powered.
This design will not work. What is shown is a prototype where the builder is underestimating how much energy he is putting into the system. The system will not generate enough energy (due to friction and conversion loss) to continually power itself when he eventually does close the cycle.
Free energy 1 magnet disk
There is insufficient detail shown to understand what the claim is here.
Screw Magnet Motor - Already covered under #2 above.
perpetual motion machine selfrunning: Category 4: Long running machine?
There isn't enough detail here to be sure, but it looks like merely a long running machine, that will eventually wind down. Note that it makes a considerable noise, so it fails to be a machine "without losses or friction" - the sound energy being lost is evidence of that.