3D cube files can be used in Photostory, however they must be dragged on to the video/image object using the built in File Explorer or Windows File Explorer.
Unlike Movie Studio they are not recognised when installed into the appropriate folder(s) for Photostory.
Your posts here have been hidden because they have nothing to do with the subject of this thread.
Please do not hijack another user's thread in this manner but rather start a new thread with your question, giving as much detail as possible about your computer and the specifics of the video files you are trying to use.