To get YouTube working on 4.4.2 today, you must disable (by patching the APK) or install a user certificate (MITM proxy). This makes the device vulnerable to CVE-2014-7911 (a SystemUI elevation of privilege) and CVE-2015-1474 (the infamous libstagefright RCE via a malicious video thumbnail).
This is where the "deep piece" gets interesting. Developers on XDA-Developers and 4chan’s /g/ board have created that run on 4.4.2.
The simplest way to access YouTube on KitKat is through a mobile web browser rather than the app.
