How do you put movies on it then from iMac?
Easy. Go onto your iMac and Google a free program called "Android File Transfer". Once loaded and installed/running, plug in your Nex7 with the supplied microUSB cord that comes with it and drag and drop files at will between the iMac and Nex7. When done eject the Nex7,like any other external drive.
Of note, you'll want to download a video player like MX Player, so you can watch any video format.
Or if you use Dropbox and have more than the standard 2gb of space, they is an awesome Android app called Dropsync that will automatically sync any file back and forth from your Dropbox (you create or use a folder or folders in Dropbox for syncing) and then any file added to that folder from any device running Dropbox (ipad, iphone, pc, Android tablet, etc) will automatically show up on your Nex7, to the folder you specify on the home drive. You never have to even touch Dropbox again on the Nex7.