Correct. Surge protectors on INPUT to UPS, not on output.
Having them on output side can also present a load/short to the UPS which it tries to compensate for by boosting output. A vicious circle.
I think the unit is fine and just gone a little noisy. You could replace them and the problem will remain. Because the noise is load variable, I would be scoping the output for spikes or looking further back in the circuit.
Try a paper towel roll as a "stethoscope" to pinpoint the noise. Try moving components with a wood or plastic tool to see if they're just resonating from the switching circuit. It's why PSUs have that glue/caulk around coils and caps.
They make noise when making power. Nature of the beast.
T
PS: I'm now seasick from watching that video....
Some folks have -NO- camera skills...
