Full screen mode for apps topic

I am running stock android 4.2.2 unrooted and I notice that some apps will utilise the full screen by hiding the navigation and notification bars when streaming video content. This occurs in apps such as Netflix, youtube, play movies, skygo and, I am sure, many others too. Unfortunately, in apps such as BBC iplayer, ITV player, BBC sport, the navigation bar remains.
I am aware that solutions for this can be found using root methods but, my question is, can the apk of individual apps be edited so that I can have this ability on an unrooted system?