simple web front for https://github.com/rg3/youtube-dl

index.php

<?php

$ytdlPath = '/whereever/your/youtube-dl'; //change this

ob_start();

$url = trim(rawurldecode($_SERVER['QUERY_STRING']));
$qStr = parse_url($url, PHP_URL_QUERY );
parse_str($qStr, $get);
if (!isset($get['v']) || !preg_match('~[a-zA-Z0-9_-]{11}~',$get['v']) ) {
    die();
}
$titleCommand = escapeshellcmd('python2.7 -u ' . $ytdlPath . ' --youtube-skip-dash-manifest --skip-download --print-json http://www.youtube.com/watch?v=' . $get['v']);
$json = shell_exec($titleCommand);
$info = json_decode($json, true);
$title = $info['title'];

$downloadCommand = escapeshellcmd('python2.7 -u ' . $ytdlPath . ' --youtube-skip-dash-manifest -q -o - http://www.youtube.com/watch?v=' . $get['v']);

$descriptorspec = [
   0 => ["pipe", "r"],
   1 => ["pipe", "w"],
   2 => ["pipe", "w"]
];
ob_end_clean();

header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename="' . $title .'.mp4"');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');

$process = proc_open($downloadCommand, $descriptorspec, $pipes, realpath('./'), array());

if (is_resource($process)) {
    while ($s = fgets($pipes[1])) {
        print $s;
        flush();
    }
}

proc_close($process);