YouTube-Downloader

This script will allow users of your site and you can easily download any video from YouTube. It is possible to download video of different quality (from mp4 to 3gp). It is also possible to download an audio track from YouTube video. The script is very simple to install, it is not very resource intensive. The script supports all legacy (and not very) versions of php. Maintained by soykothasan on GitHub, where it has earned 35 stars from the community.

It's actively developed around youtube, download, php, and is a solid reference for anyone building with these tools.