I don’t know how much you know about AP – so maybe you know this already – AP has import for exactly this reason. When you import a sequence of frames (png’s, jpg’s or animated gif) AP will automatically put them in a special layer called reference layer. Then you just add a normal layer on top and draw your rotoscoping.
But maybe you are asking about the need for importing a movie file instead? This will come soon. One of the relatively few things left on our todo list is import of mp4 and mov clips.
Looking forward to your response.