As I did not notice you had a GitHub repo to make a pull request, I dropped your code to my GitHub:
github.com/grrinch/php-classes/tree
...
I made a little change in your _embed() function, changing preg_replace to PHP's native functions. I do not rely on preg_replace that much, as YT has many variations of the link.
My version takes any YT link, converts the query string to an array and takes the "v" parameter into the iframe html source.
Obviously, a check making sure it actually is a YT link schould be in place, but I might update it later if you're OK with the code being in my repo.