I haven't seen the Harry Potter one, but the one I have is like a normal frame, you download the photos you want onto it, plug it in and it shows the photos in turn, staying on some longer than others, it doesn't seem to go through them in the same order each time. It's fantastic if you take lots of photos and can't decide which ones to put in the frame.
Have a look:
http://www.digitalframesdirect.com/?gclid=CPypxt6i8I0CFQMfEgod1l_KOg