imovie on iMac doesn't find movies on my iPad when trying to import. Moviues are in iPhoto, but not iMovies....

Hi. Just bought an imac, to centrally store all the pictures and particularly movies clogging up our 2 ipads.

connected the first ipad, and in imovies the movies appeared and were imported as expected. I then connected the second Ipad (a mini), and now imovies only recognises the photos on this one. The movies on the second ipad do appear in iphoto, and i suppose i could just store them all in there, but would prefer to keep all my movies in the obvious place, i.e. imovies!

Any thoughts or pointers on how to get this to work? thanks.