Alternatif olarak curl ile çekebilirsiniz.

$go = "https://www.instagram.com/p/Bf5W-R_l9Sc/";
$url = "https://api.instagram.com/oembed/?callback=&url=" . $go;
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, $url);
curl_setopt($curl, CURLOPT_REFERER, "https://google.com");
curl_setopt($curl, CURLOPT_USERAGENT, "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/60.0.3112.113 Safari/537.36");
curl_setopt($curl, CURLOPT_FOLLOWLOCATION, 1);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_HEADER, 0);
curl_setopt($curl, CURLOPT_TIMEOUT, 30);
$result = curl_exec($curl);
$result = json_decode($result, TRUE);

echo $result['media_id'];