Surprisingly, the mobile website ( m.youtube.com ) inside a lightweight browser like Opera Mini or Via Browser works decently on KitKat. It lacks polish but plays videos reliably.
Google has signaled that by late 2026, even older YouTube API endpoints will begin shutting down. This means that while version 15.x works today, it may eventually fail to load videos due to backend changes. Android Kitkat 4.4 4 Youtube Apk Download