Here's a good place to start: https://developers.g...getting_started ...
Then check out this link: http://www.youtube.c...on=3&autoplay=1
Confusion arises when we forget that only certain versions will actually autoplay -- I cite version=3.. then the option "...?version=3&autoplay=1" should work when tagged on the end of the video URL.
Also try this link: http://www.becca-black.com/.
Good luck.
EDIT:
To be more specific: https://developers.google.com/youtube/player_parameters