If the function isn't called when you added it some add_action, there are 2 possible cases: 1. You entered wrong action/filter hook name. 2. Your loaded page doesn't trigger that hook.

In this case you did the 1st. There is not a hook called: wp_enque_scripts, there is not a function called wp_enque_scripts. Change them to wp_enqueue_scripts.

add_action( 'wp_enqueue_scripts', 'video_bg', 10);
add_action( 'after_setup_theme', 'post_theme_setup' );

if ( !function_exists( 'post_theme_setup' )):
function post_theme_setup(){

    function video_bg() {
        wp_enqueue_scripts( 'myVideo', get_stylesheet_directory_uri() . '/JS/filmScript.js', array('jquery'), '1.0.0', false );
        echo '<script>console.log("Script added?")</script>';
    }

    add_action( 'wp_enqueue_scripts', 'video_bg', 10);
    echo '<script>console.log("Loop Entered")</script>';

}
endif;

You can also optimize your code like that:

add_action( 'after_setup_theme', 'post_theme_setup' );

if ( !function_exists( 'post_theme_setup' )):
function post_theme_setup(){
    add_action( 'wp_enqueue_scripts', 'video_bg', 10);
    echo '<script>console.log("Loop Entered")</script>';

}
endif;

  function video_bg() {
        wp_enqueue_scripts( 'myVideo', get_stylesheet_directory_uri() . '/JS/filmScript.js', array('jquery'), '1.0.0', false );
        echo '<script>console.log("Script added?")</script>';
    }