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// Get youtube ID from url
// http://www.ajagwe.com/how-to-grab-youtube-video-id-from-url-in-php/
function youtube_id_from_url($url) {
    $pattern =
        '%^# Match any youtube URL
        (?:https?://)?  # Optional scheme. Either http or https
        (?:www\.)?      # Optional www subdomain
        (?:             # Group host alternatives
          youtu\.be/    # Either youtu.be,
        | youtube\.com  # or youtube.com
          (?:           # Group path alternatives
            /embed/     # Either /embed/
          | /v/         # or /v/
          | /watch\?v=  # or /watch\?v=
          )             # End path alternatives.
        )               # End host alternatives.
        ([\w-]{10,12})  # Allow 10-12 for 11 char youtube id.
        $%x'
        ;
    $result = preg_match($pattern, $url, $matches);
    if (false !== $result) {
        return $matches[1];
    }
    return false;
}

 // echo youtube_id_from_url('http://youtu.be/NLqAF9hrVbY'); # NLqAF9hrVbY