Hi, may I suggest to add as dependecies gst-plugins-libav when gstreamer use flag is enabled. So in this way youtube works out of the box. Thanks
And what if someone else finds they do _not_ want media-plugins/gst-plugins-libav installed, but with your change we're suddenly forcing them? So it's better for everyone that you emerge media-plugins/gst-plugins-libav when you find that you need it.