First of all thanks for this cool little helper, I use Youtube shortcode on a lot of my client's sites. I recognized that Youtube shortcode is not working properly on WordPress 3.5 (using Thesis Framework 1.8.5).
(these are two different WordPress instances btw)
I cannot exactly say if it was the Update to WordPress 3.5.1 that killed the plugins output or if it was my Upgrade from Thesis 1.8.4 to 1.8.5 that I did lately. But it did work some weeks ago...
Thanks for your help!