There are some problems with your solution.
1. To get your match into $1, it should be m/(matchingStuff)/. That is, there needs to be parens.

2. Your 'if' statement should be if ($match_count == 3). This is a numerical comparison.
Try this:

my @matches;

open (F,"files.txt") || die ("Couldn't open file: $!\n");

while(<F>) {
    chomp;
    if (/matchingstffHere/) {
        push(@matches, $_);
    }
}
close(F);
if (scalar(@matches) >= 3) {
   print "Needed = $matches[2].\n";
}
[download]