I have recently set up a quad box for my nestbox cameras. This piece of kit plugs into the PC and then you can plug in upto 4 cameras into the back. You can cycle between the 4 cameras or have different combinations up on screen, including all four. Today, I set it up on all four of my nestboxes along with i-catcher and it worked really well. Set up like this means that i-catcher monitors movement in all four and I could see who had visited all the nestboxes!
The only downside is that the images are small, but just for monitoring, it is great!