The main question to ask yourself is this:
Who is the intended audience?
If the audience is intended to be K-12 school children then the depth of coverage you need may not be there - or the language is simplified to the point where it is obviously not on the scholarly or academic level you need. These sources might be all right in your intial research to understand a new topic, particularly when ideas might be very abstract - but it would not be appropriate once a basic level of understanding has been reached.
If the source is for the average layperson you again may not have the depth of coverage you need either. For example, the movie "Titanic", though historical in much detail, would not be considered scholarly/academic because it tells the story from a fictionalized point of view (introduction of fictional characters, combinations of real people, situations that were compressed due to time constraints). Documentaries about the Titanic - how it sank, who was aboard, who was rescued - do not fictionalize any aspect but approach it with facts (even though it might present ideas that are theoretical in nature). In this case documentaries would certainly be a more appropriate source for research than a feature film would be.