Unable to use add_filter on network_the_content

There's a slight typo in the functions.php which means that you can't do add_filter(network_the_content

The problem is that the network_get_the_content function ends:

return $output;

when it should end:

return apply_filters('network_the_content', $output);

if you make this change other plugins can then apply their own filters on your function.