Well in personal experience Videos do not convert as well as text ads. My clients site deals with exotic car rentals. He was doing very well with his ads and suggested to me we place video ads as well. The videos were highly targeted and looked great on the site. When a viewer would click on a car there would be an ad playing about that car or a related car. It looked like it would work, however not only did it not work, it dropped his regular earnings by a 20%. When we removed the video ads the earnings went back up.
As far as earning more with videos I guess its hit and miss depending on the industry. Your best bet would be to research and read people experiences with video ads. Or you can always resort trial and error by testing different methods.