That's a fascinating idea. Unlike gmail, there isn't an upper bound on how much you can store on YouTube. If you could encode data in a way that's resilient against re-encoding, you could use YouTube for steganography as well. Or, for that matter, see http://dataliberation.blogspot.com/2012/09/your-youtube-orig... .
That said, it's also amazingly wasteful, and abusing a free service for a purpose it isn't intended for.
That said, it's also amazingly wasteful, and abusing a free service for a purpose it isn't intended for.