Q: If I want to use the i movie app on the i pad, is the 16GB good or does it need more GB?

It depends on what else you might want to have on the iPad and how many movies you want to be working with, but I'd recommend you get at least the 32GB model if your budget will allow. Movies take up a lot of space. You can't expand the storage later, so I usualy advocate buying as much as funds will allow. It's best to have more than you think you'll need.

Regards.

HD movies require much more space than SD movies.

16GB vs 32GB vs 64GB: Which new iPad storage capacity should you get?

http://www.imore.com/2012/03/08/16gb-32gb-64gb-ipad-capacity/

How much content will fit on my iPod or iPhone?

http://support.apple.com/kb/HT1867

How Much iPad Memory Do You Need?

http://ipad.about.com/od/iPad-Tutorials/a/How-Much-iPad-Memory-Do-You-Need.htm

 Cheers, Tom