Video scallers are always struggling in portrait mode. In fact even if you have a tickertape in landscape mode, and JPGs that do transition, you will get a slight pause on the text and then it carries on as normal. This happens everytime there is a change in JPG. I am afraid this is the way it is. I do use flash files, this is probably better, but you need to get the a compiler or the AVS video converter (tis is great software) and convert your files at will.
Bill