Note: This is a technical guide. For discussion of how or why you would want to use this, see some of the comments below the guide.
I played around with video feeds and cursor feeds quite a bit in the ISBoxer 38 beta and they've changed the way I setup my windows, so time for a guide. Here is a screenshot to give you an idea of where we are headed:
In the above there are 4 full screen video feeds(along the bottom), 4 smaller video feeds (just above them, showing my bags/repair on my slaves) and a cursor feed (of my mages' action bars).
A video feed is a static window into another character slot. A cursor feed is just a dynamic video feed that follows the mouse cursor. All feeds have two components: a source and an output.
Firstly, if you wish to use either video feeds or cursor feeds and have the feed region not appear at a lower resolution than your main window you may have to change your window layout so that all of the regions in your layout are the same size. To do this, delete your window layout from your character set. Using video feeds like I do in this guide means you don't need to use a window layout.
This results in all 5 game windows being the same size and being stacked behind each other. I swap between mine with hotkeys. See below for a technique to use for those of you who change windows by clicking.
See post 2 for how to setup up the feeds.