Monitoring 12 Video Feeds From Video Cameras - NEXT Or FORWARD Button On My Monitor Form

I am monitoring 12 video feeds from video cameras. Now I have more than 12 cameras, I have 134. But I will only monitor 12 cameras at a time. By Monitoring I mean, I have 12 small video screens on the form that I can see the video. The way I know which cameras are active, so I can monitor them is by a boolean value in a sql database. I run a Store Procedure in my program, and spit out the results in a XML file. I then read the XML file in a loop. This XML file will have a list of the camera names I need to monitor.

So that is for 12 video feeds. Now, I want to have a NEXT or FORWARD button on my monitor form. So when I click this it will give me the next group of cameras, 13 to 24. Now if I only have15 cameras that are active, that means the first group is 1 to 12, then the second group is 13 to 15 cameras. So I will only have 3 to monitor on the second grouping. One thought I had was to have another field in my table to mark as already as an active monitor, so when I run the SP, i will not select that row. But I need to select 12 at a time. Or I can make a number of xml files, one xml file for each grouping of 12, but I need to figure out how I can select the next group without re-selecting the first group. I have no code at the moment, I'm on my non-programming computer.