Over the past few weeks there had numerous iOS 5 tweaks which enable hidden features that are kept disabled by default e.g. Auto Correct Keyboard, Panorama Mode etc and today YouTube HD Video Playback enabler on 3G Data rather than WiFi (default) for iPhone iPad and iPod Touch. Sonny Dickson has discovered the tweak and enabling is simple and similar to Panorama Mode tweak which requires modifying backup file and restore.
Procedure to Enable Youtube HD Video Playback On 3G Data iOS 5
1. Download iBackupBot
2. Backup your iPhone/iPod in iTunes
3. Open iBackupBot and find the backup, then load it.
4. Find Library/Preferences/com.apple.youtubeframework.plist and open the file. (if your software isn’t registered you’ll have to press cancel and then it will open)
5. Add in the following code: <key>HD3G</key><true/>
6. Save your modifications, and then restore from backup from within iBackupbot.
After you have completed the procedure you will see an option to enable HQ 3G Playback under Settings > YouTube.
Source Sonny Dickson
It is expected that soon Jailbreak tweak will simple enable Youtube HD Video Playback mode and we will be posting the tweak as soon as it becomes available.