Just tried to look at the video but it says private?

It sounds very much like the licence is at fault, which sadly doesn't surprise me as I think someone else I helped with a StrikeCNC machine was given a fake (or no) licence. Illegal licences for Mach3 do exist, however most companies stop them working after software updates, so that's probably what has happened here. If they had bought a licence for you it would have your name on it. Either way you should get a licence, or dare I say it, try LinuxCNC as it's free.

If re-installing you need to keep the .xml file which stores the settings for your machine and the licence file, both of which are stored in "Program Files". If you want to be sure just make a copy of the whole mach3 folder and put it somewhere safe, as it's not that big.