My iPad has a series of TV shows I loaded from my old iMac to my iPad. I now have a new iMac and no method I am aware of to get these videos transferred to the new iMac from my iPad. The videos were downloaded outside if iTunes so that's no help.
I have not heard of sharepod but will look into it.
When the iPad is plugged into my computer and iTunes is opened up the only option is to erase and sync.
As the video was not purchased that option is not available to me.
Is your new Mac's iTunes authorized with your Apple ID under the Store drop down menu?