That P (simply read ) stands for (" **P** roducer"). Traditionally, P has been used like a name suffix for a super-high executive in the showbiz/broadcasting/anime industry (someone even higher than a "D", or /director). However, after the success of the _Idolm@aster_ franchise, where a "producer" has a role closer to that of an agent or a manager, this "P" suddenly became a very common suffix for amateur creators on YouTube and Nicovideo. You can read more about this on this Nicopedia article (in Japanese).
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> PPproducerP
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> P(PV)
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> VOCALOIDUTAUMikuMikuDanceVOCALOID()P P20079 POSTER projectikakz ryo
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