The 16 channels was showing live streams of 16 channels that was on Telewest at the time.
They has Sky One on it with "21" on that screen. And Sky Movies Plus on it with "45" on that screen. All 16 channels has to be broadcasting 24/7.
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Something like the start of the following YouTube video but 4 channels added in the middle.
https://www.youtube.com/watch?v=QyThnH2jZlY