In or out make no sense. However, works and doesn't work do. For video (and I think that is where the problem lies) vertical seldom works. While a still captures an instant in time and portrait or landscape may be valid choices in may instances, video is capturing an extended period in space. With video context is frequently, or rather most often, a vital piece. A landscape orientation captures the context and environment better in most cases. I guess a space shuttle launch might be an exception and may very well be better in portrait due to the direction of travel. But I can't think of very many other times it will work well with video.

While I am on this rant, why do so many GPS units in cars default to landscape? In this case I want portrait. I am more interested in where I am heading than what is off to the side.