Video content is crudely defined. If something is not very short (<10 minutes) then it tends to be considered long-form. But there is a middle ground - one which displays a distinctive combination of characteristics in terms of production, broadcasting and viewing.
Mid-form video (between 10 and 20 minutes) has the ability to carry the narrative arcs normally associated with long-form programming, whilst also retaining the snackable and shareable attributes of short-form.
The footprint of mid-form is, so far, small. However, it is growing, as its unique qualities, such as excellent ad completion, become more readily recognised.