Just saw the uploaded video from today on YouTube.

I am in no way guaranteeing this will work in order to attach to a process in NSight, but I do have to attach to a lot of processes for malware analysis in Windows and many times, I have to right click the exe (in this case, you would right click NSight) and Open As Administrator in order for the processes to appear in the process list to attach to.

If you already tried that, then slap me, but I just wanted to bring it up in case you hadn't.