bp_media_delete_activity_media( $activities )

function bp_media_delete_activity_media( $activities ) {
	if ( ! empty( $activities ) ) {
		remove_action( 'bp_activity_after_delete', 'bp_media_delete_activity_media' );
		foreach ( $activities as $activity ) {
			$activity_id = $activity->id;
			$media_activity = bp_activity_get_meta( $activity_id, 'bp_media_activity', true );
			if ( ! empty( $media_activity ) && '1' == $media_activity ) {
				$result = bp_media_get( array( 'activity_id' => $activity_id, 'fields' => 'ids' ) );
				if ( ! empty( $result['medias'] ) ) {
					foreach( $result['medias'] as $media_id ) {
						bp_media_delete( $media_id ); // delete media
					}
				}
			}
		}
		add_action( 'bp_activity_after_delete', 'bp_media_delete_activity_media' );
	}
}