I have a working function that adds a meta field to all attachments (so I can enter the url of a video). I would like this field to populate only on attachments in the "video" category.

I've tried the below, by adding `in_category('video')` but that didn't work.


    function attachment_field_url( $form_fields, $post ) {
        
        	$form_fields['video-url'] = array(
    		'label' => 'Video URL',
    		'input' => 'text',
    		'value' => get_post_meta( $post->ID, 'video_url', true ),
    		'helps' => 'Add video URL',
    	);
    
    	return $form_fields;
    }
    
    add_filter( 'attachment_fields_to_edit', 'attachment_field_url', 10, 2 );
    
    function attachment_field_url_save( $post, $attachment ) {
        
        if( in_category('video')  && !isset ($attachment['video-url'] ) )
    update_post_meta( $post['ID'], 'video_url', esc_url( $attachment['video-url'] ) );                             
    	return $post;
    }
    
    add_filter( 'attachment_fields_to_save', 'attachment_field_url_save', 10, 2 );