davido's answer is good if you can get your data straight from the top. If not, this makes a little map for you and gives the output you're looking for.

my %channel_map;
for my $channel ( keys %files_by_channel )
{
    $channel_map{$_} = $channel for keys %{ $files_by_channel{$channel
+} };
}

printf "%-10s %-15s %-40s\n", 'File#',  'Channel Name', 'File Name';
printf "%-10s %-15s %-40s\n", '-' x 10, '-' x 15,       '-' x 40;

for my $file_number ( sort keys %files_by_number )
{
    printf "%-10s %-15s %-40s\n",
             $file_number,
             $channel_map{$file_number},
             $files_by_number{$file_number};
}
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