I would echo McDarren's sentiment above. If you can't be absolutly sure what your HTML will look like (and, in my experience, you can't) it is usually best to use an HTML parser.

This uses HTML::TokeParser::Simple.

#!/usr/bin/perl

use strict;
use warnings;
use HTML::TokeParser::Simple;

my $html = do {
  local $/;
  <DATA>;
};

my $p = HTML::TokeParser::Simple->new(\$html);
my ($table, $start);

while (my $t = $p->get_token){
  $start++ if $t->is_start_tag('tr');
  next unless $start;
  last if $t->is_start_tag('br');
  $table .= $t->as_is;
}

print "*$table*\n";

__DATA__
<title>stuff</title>
<br>Header</br>
<tr>
  <td>1</td>
  <td>2</td>
</tr>
<tr>
  <td>3</td>
  <td>4</td>
</tr>
<br>Trailing Info
[download]

Output:

---------- Capture Output ----------
> "C:\Perl\bin\perl.exe" _new.pl
*<tr>
  <td>1</td>
  <td>2</td>
</tr>
<tr>
  <td>3</td>
  <td>4</td>
</tr>
*
> Terminated with exit code 0.
[download]