Video in colorbox: incorrect size with picturefill, use weblinc

To show a youtube video in colorbox you can use this code:
<a class="colorbox-load" title="TITLE" href="http://www.youtube.com/embed/W5eFEBd0GS8?width=640&amp;height=480&amp;iframe=true&amp;rel=0">youtube video</a>

You must enable colorbox load in colorbox settings.

But if you have the Picture module the video is presented in a wrong size. I did some tests and it happens when picturefill javascript library is selected in the Picture settings page (/admin/config/media/picture/settings). Picturefill is the default library but Picture comes with another library that do not generate this resizing problem.

If you have Picture 7.x-1.2 you can use weblinc library
If you have Picture 7.x-1.x-dev you can use eitherweblinc or picturefill 2.0 library.

I tried to use Picture 7.x-2.x-dev but I get errors to update it, so I don't konw how it works.