GrabYoutubeID

<?php
# https://github.com/eyecatchup/php-yt_downloader/blob/master/youtube-dl.class.php#L259
# https://gist.github.com/ghalusa/6c7f3a00fd2383e5ef33
# https://stackoverflow.com/questions/2936467/parse-youtube-video-id-using-preg-match
# https://hotexamples.com/examples/-/-/parse_yturl/php-parse_yturl-function-examples.html

# Função simples para obter o id do video do Yoututbe
function GrabYTID ( $url ) {
    preg_match('%(?:m\.|)(?:yout.*)(?:[^\/]+\/|.*[?&]v=)([^"&?\/]{11})%i' , $url , $matches ) ;
    return ( isset ( $matches[1] ) ) ? $matches[1] : $url ;
}

$urls = array(
    'http://www.youtube.com/watch?v=4heZkvPcd1M&feature=c4-overview-vl&list=PLbzoR-pLrL6qucl8-lOnzvhFc2UM1tcZA',
    'http://www.youtube.com/sandalsResorts#p/c/54B8C800269D7C1B/0/4heZkvPcd1M',
    'http://www.youtube.com/embed/4heZkvPcd1M',
    'http://www.youtube.com/user/username#p/u/11/4heZkvPcd1M',
    'http://youtube.com/vi/4heZkvPcd1M?feature=youtube_gdata_player',
    'http://www.youtube.com/?feature=player_embedded&v=4heZkvPcd1M',
    'https://www.youtube.com/watch?v=4heZkvPcd1M&list=RDFZu097wb8wUx',
    'http://www.youtube.com/watch?feature=player_embedded&v=4heZkvPcd1M',
    'http://www.youtube.com/v/4heZkvPcd1M',
    'http://www.youtube.com/e/4heZkvPcd1M',
    'http://www.youtube.com/p/4heZkvPcd1M',
    'http://www.youtube.com/?v=4heZkvPcd1M',
    'youtu.be/watch?v=4heZkvPcd1M',
    'youtube.com/watch?v=4heZkvPcd1M',
    'm.youtu.be/watch?v=4heZkvPcd1M',
    'm.youtube.com/watch?v=4heZkvPcd1M',
    'http://www.youtube.com/watch?v=4heZkvPcd1M',
    'http://www.m.youtube.com/watch?v=4heZkvPcd1M',
    'http://www.m.youtu.be/watch?v=4heZkvPcd1M',
    'http://youtu.be/4heZkvPcd1M',
    'https://youtu.be/4heZkvPcd1M',
    'youtu.be/watch?v=4heZkvPcd1M',
    'youtube.com/watch?v=4heZkvPcd1M',
    'https://youtu.be/4heZkvPcd1M',
    'https://www.youtube.com/embed/4heZkvPcd1M',
    'https://www.m.youtube.com/embed/4heZkvPcd1M',
    'http://youtu.be/4heZkvPcd1M',
    'http://www.youtube.com/embed/4heZkvPcd1M',
    'http://www.youtube.com/watch?v=4heZkvPcd1M',
    'http://www.youtube.com/watch?v=4heZkvPcd1M&feature=g-vrec',
    'http://www.youtube.com/watch?v=4heZkvPcd1M&feature=player_embedded',
    'http://www.youtube.com/v/4heZkvPcd1M?fs=1&hl=en_US',
    'http://www.youtube.com/ytscreeningroom?v=4heZkvPcd1M',
    'http://www.youtube.com/watch?NR=1&feature=endscreen&v=4heZkvPcd1M',
    'https://m.youtu.be/4heZkvPcd1M',
);
echo count ( $urls ). "\n" ;
foreach ( $urls as $url ) {
    var_dump ( GrabYTID ($url) ). "\n";
}