Echo video length?

Sure. And you don’t need to use my plugin to do it. This information is actually built in to WordPress for most video formats since version 3.6. It’s stored in the _wp_attachment_metadata array. You’ll probably want to use the length_formatted key. Here’s an example assuming you have the video attachment ID stored in a variable $attachment_ID :

$video_meta = get_post_meta( $attachment_ID, '_wp_attachment_metadata', true );
echo $video_meta['length_formatted'];

It doesn’t matter much, but I think it would also work with the function wp_get_attachment_metadata

$video_meta = wp_get_attachment_metadata( $attachment_ID );