true, but if you actually look at the page there is no where on there where they are doing that. the video, was given credit the first time they posted it, and the book cover they never said they created and owned, so where are they saying what they post is their own?
Regardless... the artist should always be given full credit for their work. Some acknowledgment should be made by the people who run that Facebook page. Especially when it is fan-made work, which is often done for free. Everytime they posted that video, they should have given it's original creator credit - not just once. If they are posting the work of others to push a personal pet project, they should be acknowledging those artists and asking permission to use their work.