I'm little lost here. I have a basic master-detail aplication, and I want to change the detail view according to the selected row in MasterViewController, but the views have different content, one has an image gallery, and the other one will load a video on full screen. It's not just refresh the detail view, have to load another view. How is the better(fast) way to do that?
I'll suggest you to use a replace segue.
Just create a segue to the desired view initiated by your row with a Style: Replace, and Destination: Detail Split.
Segues were introduced in the iOS 5 SDK
EDIT:
These are step-by-step instructions to accomplish what you need. From now on:
just a bit for naming for ease of explanation
That's all.
More on segues: http://www.scott-sherwood.com/?p=219