Install TubeFixer for iOS
TubeFixer for iOS works on iOS 3.0 through 5.1.1 on both the stock app and the App Store app, and it will remove the update nag from the iOS 6 YouTube app.
Install with Cydia
Alternatively you can add the repo
cydia.invoxiplaygames.uk in Cydia and install TubeFixer for iOS from there.
View Package Page
TubeFixer for WiiMC
WiiMC (a Wii homebrew media player) is also supported by TubeFixer! While not as feature-filled as the stock Google YouTube Wii app, it still serves as a way to watch YouTube on your Wii.