This is completely untested and I'm sure a lot more wordy than it needs to be, but I'm tired and didn't feel especially graceful :^).

my $cntr = 0
my $stuff = ""

LINE: while(<HTMLFILE>) {
      if($cntr == 0 && $_ !~ /$myregex/) { next LINE; }
      last LINE if $cntr >= 5;
      $stuff .= $_;
      $cntr++;
}
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