Quick test: Noise on Nex-7 video
I tried to find out what the impact of the ISO on video on the Nex-7, so I cycled through with the lens cap on. The noise was not that visible so I tried to do what you usually try to avoid. I added brightness and sharpening.
Let me know, what you think. For me it prooves my experiences, that videos start get noisy with ISO bigger than 800.