Ubuntu Plesk 12.5 fresh install Wordpress can't embed

I just installed Ubuntu Plesk 12.5 from official Plesk site, all is working perfectly but wordpress won't embed any video. I noticed that sometimes it works but if i try to embed another link it fails and displays the url not the embedded content.
The only specificity is the plesk host is natted but correctly configured in Plesk network settings

thanks in advance