Hi Difficult to make out sound from video , but, the only things I can think of, that move, Fan, and pump ? Is this noise with the burner on ? If so kettling, but not sure it sounds like that. It could be the settings in the gas valve, you need the analyse the products of combustion, and check the co2 readings I have heard odd noises when the co2 setting need adjusting. Regards Peter
You need a combustion analysis on that it does sound like the gas valve but as others have said hard to tell from the video