All conventions, including form conventions are contextual and cultural dependant. They also change over time and can be affected by trends.
Each different type of media has it’s own form conventions that audiences come to expect and which makes the media product easy to read. Form conventions are about the way that media products are constructed.
In video based media products, one important form convention is continuity editing.
Continuity editing is a system of creating a narrative together for the audience that is is smooth and seamless. It is designed so that you forget about the construction of the narrative and become involved in the story.