Everybody knows that youtube has simple editor where you can define few options. But in fact youtube watch (and embed also) url has much more options. Here you can find some of them i was able to find and test.
Usage: http://www.youtube.com/watch?[sequence of parameters]
The v parameter specifies the
VIDEO_ID. Unique alpha-numeric ID of the video.
The t parameter allows to define start time of video in the form of
The hl parameter prompts the user(host) to a specific the indicated language
English (Great Britain, Ireland, Australia and New Zealand)
English (United States and Canada)* default value
The gclid parameter is used in auto-tagging for Google Ad Words and will show up in the landing page URL when a user arrives at the page from the ad.
The feature parameter is assigned within Youtube to describe certain videos and where display
Any videos in response to a video will have this parameter linked to it. (Assigned within youtube)
The reverse of the above. The “child” video page will have a link to the “parent” page (Assigned within youtube)
Promoted Youtube Video (pyv) on a watch page (Must be entered within Google AdWords Editor destination url)
Promoted Youtube Video (pyv) on a channel page (Must be entered within Google AdWords Editor destination url)
The kw parameter is an indication of keyword insertion. Keyword insertion is an advanced feature that can help make an ad more relevant to a diverse audience. Each time the ad shows, AdWords will automatically replace the code with the keyword that triggered the ad. (Must be entered within Google AdWords Editor destination url)
Not clear yet:
&ad= Advertisement Id assigned to an advertisement ?
&feature=recentlik Recently Liked ?
&playnext=[1 or 0]
&list=QL Queue List ?
&index=[INDEX_NO] Index of