I have this problem ever since i bought this tablet (n8010). When i watch YouTube and press on full screen, the lower bar (System, Navigation, Notification bar) won't hide. It happens with every rom i tried, original or custom, rooted or unrooted. A couple of friends of mine have the same tablet and when they watch YouTube it works just fine. Also, on my Note, using different video apps, the System Bar does hide while watching in full screen. I also don't think its the YouTube app's fault because on my Nexus 4 it works fine with the latest version of YouTube and i also tried deleting the update and watch with an older version but that didn't work as well.