a PHP script that wraps around youtube-dl which allows you to enter in a youtube ID. The script then downloads the entire video at the highest resolution and uses javascript to write an HTML5 video element to the page which in turn autoplays the video you just downloaded.
this is a terrible idea and most likely against youtube's TOS - don't use it! Further, after I wrote this I found alltube (github or alltubedownload.net), which is almost identical to this project, but WAY more fancy. Use that instead!