There are 2 values in the registry that relate to YouTube.
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I TAKE NO RESPONSIBILITY IF YOU CHOOSE TO ALTER THEM - I HAVE TRIED IT AND BY INCREASING THE SIZE AND TIME LIMITS, I CAN NOW UPLOAD VIDEOS GREATER THAN 15 MINUTES
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HKEY_LOCAL_MACHINE\SOFTWARE\Cyberlink\PowerDirector\10.0
Key Name
YouTubeSizeLimit >REG_DWORD decimal value 2048
YouTubeTimeLimit >REG_DWORD decimal value 15
Play with them at your own risk!!!