check-if-youtube-video-is-private.php

function getYoutubeVideoStatus( $video_id ){
    /**
     * Get the status of a youtube video
     * @param string $video_id
     * @return string | false
     */
    $url = "https://www.googleapis.com/youtube/v3/videos?part=status&id=$video_id&key=YOUR_API_KEY_HERE";
    $results = json_decode(file_get_contents($url));

    return( isset( $results->items[0]->status->privacyStatus ) ) ? $results->items[0]->status->privacyStatus : false;
}

getYoutubeVideoStatus('imF5oTuALTo'); //false