Alright.
The regex itself is doing the match, and if the regex matches, there must be a matching string or word. And the backreferance will just put that into the memory so you can read it later on.

Here\'s my version:

on $^*:hotlink:/[+-][ohvbeIsklim]/:#: scon -r $iif($nick(#,$me,@%),return,halt)
on $*:hotlink:/([+-][ohvbeIsklim])/:#: mode # $replacex($regml(1),+,-,-,+)