open (FILE, $lfilename) or &dienice;
$/ = undef; # Slurp mode
$file = (<FILE>); # Grab the whole file into $file

while ($file =~ m/Begin Product(.*?)End Product/gs) {
    my $record = $1;
    # Now $record contains the entire contents of exactly one
    # record from your file. You can now fold, spindle, and 
    # otherwise mutilate $record to pull out the various 
    # and sundry pieces for each record.
}