I tried to find an explanation for the way it works in the manual, but I couldn't. So, I'll just note what I've found by experience. You can't actually click on the checkboxes. The checkboxes are there for the program itself to fill. In order for you to make a selection of a video, you have to simply highlight the Show/Season/Episode line by clicking the line once. Then you are able to do your action from the Context Menu, Jacket Search, etc. The checkboxes will be checked by the program itself when it wants you to click on Do Checked for it to do some type of action. I've never figured out why it doesn't just do the action (like moving a file) when it knows you need it done and does it on its own most of the time. You've hit on one of the great mysteries about TV Rename for me. I've just come to the realization that that's just how it works and to go along with it rather than think about it too much.