Originally Posted by PatriceJ

if you are not able to explain the process in your own words, without relying on the book, then you should not teach the class without first getting permission from the author. the same applies to the YouTube video - especially if it was posted by the author or publisher of the book in question.

my recommendation in this specific case is based on the fact that you would be "teaching the book/video" or "teaching from the book/video". you would be relying upon specific, copyright protected materials and, therefore, interfering with their creator(s)' ability to benefit from those protected work(s).