gst-launch-ext doesn't run with Perl 5.8 installed. This is because of the
extra 'my' for $ext in the extension sub at the top of the file (it hides
the other $ext, thus resulting in an empty results, causing problems later
when an extension is needed. The fixed extension looks like this: 

sub extension
{
  my $path = shift;
  my $ext;

  # get only the bit after the last period.  We don't deal with
  # .tar.gz extensions do we ?
  if ($path =~ /\./)
  {
    my $ext = $path;
    $ext =~ s/^.*\.//;
  }
  else { $ext = ""; }

  return $ext;
}sub extension
{
  my $path = shift;
  my $ext;

  # get only the bit after the last period.  We don't deal with
  # .tar.gz extensions do we ?
  if ($path =~ /\./)
  {
    $ext = $path;
    $ext =~ s/^.*\.//;
  }
  else { $ext = ""; }

  return $ext;
}