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This vaguely reminds me of Aardman's 'Stage Fright' (I haven't seen it since I was a kid so my memory is hazy too), however I don't think it is what you are looking for. Worth a shot anyway.
I've seen Stage Fright too, so no, not the one. But thanks anyway.
I think I can help you here, it's called Petrushka, it's a kid's TV adaptation of a ballet by Igor Stravinsky.
There's this old stop-motion film I remember seeing on TV when I was younger, but the only part I remember with any clarity is the ending. It's about this old man and his two grandchildren in a hut in the snowy woods, where he sits by the fire and tells them a story from when he was young, and working with a puppet show. One of the puppets 'dies' during a performance, and then the audience wanders away, leaving him alone with the puppet. Then, during the night, the puppet's ghost appears and scares the bejesus out of him. Then, once that's done, the old man and grandchildren just sit there in dead silence, staring at one another, until the camera pans out of the hut and the film ends.