I\'m looking for the way to get big facebook video thumbnail. i\'ve found some links:
http://graph.facebook.com/1571886379501082/picture ~> this one retun one small thum
This method will create an object array and seek the last key of the format, which is the big image.
$fb = file_get_contents('http://graph.facebook.com/1246538155392772');
$fb = json_decode($fb);
//---find the big image which is always last in array
$key = count($fb->format)-1;
$bigimg = $fb->format[$key]->picture;
echo '';
If you just want to get the image for simple posting, just use this tool. Get Facebook Video Images