How to download video and audio combined?

[jeraldpunx]

I tried this on my php, but the audio and video are separated in direct link.

<?php
$url = $_POST['video_link'];
$cmd ='youtube-dl -g --all-formats ' . escapeshellarg($url);
 exec($cmd, $outputsd);

I am planning to list all links like
1080p
720p
480p
360p

[dstftw]

https://github.com/ytdl-org/youtube-dl#format-selection