Vimeo froogaloop

so I’m not sure the enqueuing is even happening

No, it’s not, because you only registered the scripts, but never enqueued them — which should be done using wp_enqueue_script().

Also, you should make frogaloop as a dependency for your snippet.js script. Hence, register the frogaloop script before your snippet.js script.

// Register the scripts.
wp_register_script( 'frogaloop', 'https://f.vimeocdn.com/js/froogaloop2.min.js', array(), null );
// The third parameter is the script dependencies.
wp_register_script( 'snippet', get_template_directory_uri() . '/js/snippet.js', array( 'frogaloop' ) );

// Then enqueue them. But you just need to call:
wp_enqueue_script( 'snippet' );
// because frogaloop will also be enqueued because it's a dependency for your
// snippet.js script.

Now that should work.