I am literally desperate and I am looking for the kind help of a more experienced developer.
The following page has in theory one you tube video embedded in it:
However it never shows in any browser and what is more if I run any debugging tool it comes up with the following error:
Blocked a frame with origin "http://www.youtube.com" from accessing a frame with origin "http://constantinostsiliacos.com". Protocols, domains, and ports must match.
I tried a few solutions which go from altering a couple of lines in wp-admin/default-filters.php which apparently have to do with allowing external iframes (http://www.krazyworks.com/disabling-wordpress-x-frame-options-support/) to disabling all plugins but no luck so far, and a few other ideas like attempting to use embedding plugins.
However the problem seems to be related with the theme I am using because if I switch to Twenty Eleven the iframes appear just fine.
I am using Chris Coyer's Blank theme (http://digwp.com/2010/02/blank-wordpress-theme/) and have other websites done with it and never had such problem.
My kingdom for a solution. Thanks a lot!