The video content is totally controlled by YouTube. What we can do is simply changing the YouTube URL parameters in the mcVideoPlugin.js.
I am not sure if your requirement can be accomplished by changing the YouTube IFrame src URL parameters. You can search for the possibility by studying YouTube's API: https://developers.google.com/youtube/player_parameters
If there is a parameter that will help, you can open the mcVideoPlugin.js with Notepad, search for:
and add or update any parameters that you like
The link below shows how Luca did some changes to the YouTube IFrame url: http://www.menucool.com/1745/Enable-annotation-Youtube-video