YouTube has long made it easy to share and embed videos into websites by giving you the HTML code to just copy and paste wherever you like. Over the years, different technologies have been used to play videos on the web, from Flash object elements to pure HTML5. YouTube's newest API for adding videos to web pages takes care of the technology, automatically choosing the best delivery method on a user by user basis.
YT did have something called the "YouTube JavaScript Player API" but this is out of date so don't use it. Instead use the new...