The official rule is "Choose your primary source. It can be anything! From a TV series to a web series to music videos or vlogs to behind the scene footage to a movie. But it should be between One and a half and 2 hours long, so two episodes of a TV series or a single film, etc. In general, we recommend that you use only this source for all the exercises, but if a particular activity sparks a creative idea and you want to expand or swap your source, of course you can!"

That said, you can choose to break any Vexercise rule you want.