<?php
$file_get = 'httрs://anothersite.ru/video.mp4';
$name = basename($file_get);
$headers = get_headers($file_get, 1);
$filesize = $headers['Content-Length'];
header('Content-type: video/mp4');
header("Content-disposition: attachment; filename=$name");
header("Content-Length: ".$filesize);
readfile($file_get);
exit;
?>