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Mamya - // You've chosen a poorly synched video of that 28 year old celebration. //
Apologies for the delay getting back on this -
You are absolutely correct, and I can see from your clip, as opposed to the badly edited (!) version that I posted, that Richard was indeed playing and singing live, and I withdraw my original view from my OP.
In my defence, that was the only version I happened across, and I think my view, based on what I believed I saw, was valid, but hey, we all make mistakes, that's why they put rubbers on the end of pencils.