I'm sure I know the answer to this questions but it is worth asking just in case. When downloading a movie they give you a choice of hd and sd. In the interst of saving space on my kids iPads... I like the sd version but if we plug the iPad into the tv I'd like the HD version. Is there any way to get the sd version if you download the hd... Or is it just one or the other even if I order the more expensive one?