The second portion of code didn't display well. Look here :
'validation' => array(
'rules' => array(
'vm_video_group' => array(
"vm_video_link" => array(
'url' => true,
),
"vm_video_legend" => array(
'required' => true,
),
),
),
'messages' => array(
'vm_video_group' => array(
"vm_video_link" => array(
'url' => __( 'Ce champ doit être une url valide', 'vm' ),
),
"vm_video_legend" => array(
'required' => __( 'Ce champ est requis', 'vm' ),
),
),
),
),
