Such YouTube videos are copyrighted by YouTube themselves.
If you need to download any videos hosted by them you will need to contact them directly for permission. They may then give you advice how to download them.
Other than that, no further information can be provided in these forums, so I am locking this thread.
Is there a safe program that you can use to download You Tube videos???
Someone said that the below link is safe:
By the way, I use the Firefox Browser and someone said the below add-on
is not safe:
Fast Video Download 1.6.1