Youtube is doing it for specific accounts yeah, I dont get this fascination with making websites for mobile devices. Most of the large services have a dedicated mobile app, if you on a phone use the app, if you on a pc use the website, and as such that website should be optimised for PC viewing. In the early days of web dev for mobile, they used to do user agent checking and serve the page for that device, but once mobile usage exploded, they decided to ditch the system, and many vendors just started redesigning their websites with lots of empty white space, simplification etc.