Subwoofer of LG home theater system

I have an old LG home theater system LH-D6240 which now showing weird noise in its sub woofer, when the volume is set above 20 (in its display) what might be the reason? can anyone identify the problem is ? i am posting a video for a better look, sorry for the low quality its recorded with my mobile camera.

I was taught to always suspect the power supply and it's usually electrolytic capacitors.