The iPhone 4 on iOS 7.1.2 cannot directly download a YouTube app from Apple anymore, even via the “last compatible version” trick, because the backend server contract has permanently changed. However, through proxy translation or web wrappers , the hardware remains capable of streaming 720p video – a testament to the iPhone 4’s longevity and the ingenuity of legacy system preservation.
If possible, consider updating your device to a newer iPhone model or a more recent iOS version (if compatible). This will ensure you can: youtube for iphone 4 ios 7.1.2 download