$re = '/\s*sources\s*: \[\s*"(.*?)"/m';
$str = '<script type=\'text/javascript\'>var player = new Clappr.Player({
sources: ["https://stream246.uqload.com/3rfkvsgbgrw2q4drdjh7flnhb2lf6ff2m6pnbxhevplrwbk2snkkbvddzajq/v.mp4"],
preload: \'none\',
poster: "https://stream246.uqload.com/i/05/00307/jge6igyfdjim_xt.jpg",
width: "100%",
height: "100%",
disableVideoTagContextMenu: true,
parentId: "#vplayer"
});';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php