Permalinks Question: Adding a prefix ONLY in front of all posts with the ‘video’ post format

I figured out that the problem above is related to the Divi & Extra theme that is being used. That theme has it’s own functions and registered the post formats in its own way, adding “et” in front of post format. Bellow this is shown, it solved the specific issue mentioned above:

if ( is_object($post) && $post->post_type == 'post' && 'video' == et_get_post_format( $post->ID ))    {
    return $post_link = home_url('/videosnew/'. $post->post_name."https://wordpress.stackexchange.com/");
}

This is esentially what made the post format function work when using the Divi Theme:

et_get_post_format( $post->ID )

Instead of the standard WordPress post format function:

get_post_format( $post->ID )