It will match whatever line is in the file.
Say textfile.txt contains these lines:
-FQM
-LOL
-RIVER
tv-xvid
tv.xvid-FQM
etc...
if any of these are in any line recieved it will return it.
the bot says "some.show.tv-xvid-LOL"
the script will search each line in the file and if "tv-xvid" is in what the bot said, then it should return matched. Many scripters would see this as a flawed way of getting the match correctly. But it works.
