YouTube has a new EMBED option, they call "delayed cookies."
When this is selected, the embed url changes from http://www.youtube.com/...
to
http://www.youtube-nocookie.com/...
with all else remaining the same.
The jw player (I am using version 4.4) does not yet autodetect that a video href at this new url is of type=youtube, but instead falls back to type=video.
This should be handled - you'll just need to reference the video by the more standard "http://www.youtube.com/v/[video id]" format