You can grab all available direct video links a youtube video page’s source by looking for the keyword ‘fmt_url_map’ as of this comment post’s date. It’s a parameter passed into the flash player that lists all the available video links. The links are seperated using semicolons (;), with each link being escaped. Simply use javascript’s ‘unescape’ function to unescape it. Each link should be composed of two parts, a single number and the link itself seperated by a pipe symbol (|). The number is the format of the video, with 22 being the most common highest quality.

I made a small javascript page app that downloads youtube vids, but the direct links grabbed by the script seem to only work in the browser that requested the page in the script. For example, I’m using chrome and I get the direct link for a youtube vid. I open firefox and attempt to use a download manager for the link to download the lengthy video but I get 403 Forbidden responses. If I go back into chrome I’m able to download the video by pasting it in the address bar. I experimented in firefox and searched for a direct video link, then using a firefox plugin I performed the request with a bare http request header, no cookies, no user agent, nothing, and I keep receiving 403s.

If anyones interested please reply back, I’d like to know what’s the deal with this.