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Youtube videos are permitted to be up to 10 minutes long and up to 1 GiG in size. Many of them are a LOT smaller.

So in theory this limit could be 1 youtube video.

Have you made any videos before? I made a twenty minute video once and its not even more than 200 MB. It was good enough for TV quality too.

And no, I have seen some YouTube videos more than an hour long like those feature films MGM is rolling out for YouTube and random documentaries uploaded by other people.
 
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