for those having problems uninstall the iptv stalker video addon first, then do as dafatmack writes above in the pvr client 0.8.3.
when you are sure that is working, install iptv stalker video addon and try migrate the settings.
it helps if you do one thing at the time and double checks, as you experienced it can easily be confusing at first.
so take it easy one addon/step at the time, you will slowly get better and it eventually it will become a lot easier.
practice makes champ.
as said make sure one works with your credentials (numbers) and then slowly move on to next addon.
do not rush and enter lots of numbers change mac again and again, etc
if a mac fails move on to a new one do not reuse the same one right away as it still has serial attached to it until the server clear the unused mac's.
if you never had luck entering the serial and other stuff you might not need a "fresh" mac, as the one you have is probably still "fresh". heh
and if you primarily or only want iptv stalker video addon instead, start with that of cause.