Easy little function to get the video ID from any YouTube URL.

fn.quickYouTubeId.php

<php
/**
 * quickYouTubeId: Easy little function to get the video ID from any YouTube
 * URL.
 *
 * I went through a lot of snippets that perform various kinds of RegEx and
 * parse_url and what not, but I thought, since most YouTube video IDs are 11
 * characters, why not just look for the only 11-character string and extract
 * that? I can't think of a YouTube URL that'll foil this match. Can you?
 *
 * 2018-06-06 - fixed the problem with other non-video IDs in the URL
 * 2016-12-28 - modernized and made it more PSR-2 compliant and shorter
 * 2012-07-28 - fixed for underscore matching
 * 2012-07-27 - first release
 *
 * @param String $youTubeUrl The URL of the video in any format supported
 *     by YouTube
 * @return String The 11-character YouTube video ID.
 * @author Aalaap Ghag <[email protected]>
 */
function quickYouTubeId($youTubeUrl) {
    return preg_match
        "/(?:[\/]|v=)([a-zA-Z0-9-_]{11})/",
        $youTubeUrl,
        $id)
        ? $id[1]
        : false;
}

The original function didn't match underscores. D'oh! Fixed.

Awesome. After many searches and experiments, this is not only the simplest solution I found, but the only one that worked!

It doesn't work if the first query value is not video id like this:
https://www.youtube.com/watch?list=RDfRh_vgS2dFE&v=fRh_vgS2dFE

Works for :
https://www.youtube.com/watch?v=fRh_vgS2dFE&list=RDfRh_vgS2dFE

Can we do anything?

@itzmukeshy7 Slightly tricky, due to the various formats. Maybe I could make it check for v=fRh_vgS2dFE or /fRh_vgS2dFE?

Edit: Fixed it! Thanks for reporting!

You left out a "(" after preg_match.

If anyone's still looking for this, it's now available as a provider for the excellent Faker library: https://github.com/aalaap/faker-youtube