The content has to be 'age-appropriate' so look at the ratings of videos etc today and keep within those ratings e.g. no X or R rated stuff and even think carefully about MA stuff. The age of the actors also has to be considered for the content e.g. if you are using younger actors the content has to be content that they can watch so if you are using a 5 year old the content has to be appropriate for 5 year olds to watch whereas if the youngest actor is 14 then the content has to be appropriate for a 14 year old to watch.
That is certainly the way it has been explained to the students at my school.