I: When you buy a video tutorial, it says that it is a copyrighted material!
A: Your concern is just about the fixed video and audiovisual content from the actual video you own. Copyrights don’t protect ideas or facts, only the authorship that is fixed in a tangible form of expression, fixed video expression or fixed audio expression. In other words, copyright protects the way an idea is presented, rather than an idea itself.
You can't share the original copyrighted video you own, but you can recreate that idea or fact with your own production value.
Facts and ideas are not protected. If NASA goes to the moon and expends millions of dollars on their research, then any student can take advantage of their discoveries without their permission to publish your own work based on their expensive research.
Another example would be if the authors of the book on “Neanderthals” takes ten years to gather all the necessary materials and information for their work and own ideas for what they think is truth or not. At great expense, they travel to hundreds of museums and excavations around the world. But after the book is published, any reader is free to use the results of this ten-year research project to write his or her own book on “Neanderthals” without paying the original author. Obviously, your way of expression needs to be translated in a different way from the original way the creator has originally fixed their work.
Is important that if you have plans or any further question on this matter, see a copyright attorney. This is just my non-legal personal advice from my personal attorney on my specific needs that may not work for you or for your personal needs.