The snippet is used to fetch thumbnail of a facebook video from any type of URL format.

fetch_facebook_thumb.php

function get_thumb($url)
{
  $url = trim($url);
  if(substr($url, -1)=="/")
  {
    $url = substr($url, 0, -1);
  }
  $urls = [$url];
  $ids = [];
  foreach ($urls as $url) 
  {
    $tmp = explode('/', $url);
    if (strtolower($tmp[count($tmp) - 2] == 'videos')) {
        $ids[$url] = $tmp[count($tmp) - 1];
        continue;
    }
    
    parse_str(parse_url($url)['query'], $query);
    
    if (!empty($query['v']))
    {
        $ids[$url] = $query['v'];
    }
    if(substr($url, -1)=="r"){
        $ids[$url] = $tmp[6];
    }
    if(substr($url, -1)=="y"){
        $ids[$url] = $tmp[5];
    }
    
    if(substr($tmp["3"], 0, 1)=="v"){
        $matches = array();
        $t = preg_match('/=(.*?)\&/s', $tmp["3"], $matches);
        $ids[$url] = $matches[1];
    }
    if(strpos($tmp[3], "video") !== false & substr($tmp[3], -1)!="r")
    {
       $ids[$url] = str_replace("video.php?v=", "", $tmp[3]);
    }
  }
$imgurl = $ids[$url];
echo "https://graph.facebook.com/$imgurl/picture/";
}