A non mechanical noise, as in unwanted reproduction is odd from a woofer as they are typically filtered out. Yes, post the vid.

With the stereo off, unplug what ever RCA's supply the woofer chnls, then power on. This gives you an idea as to whether its coming to the amp or being generated by the amp or down stream.

Also, with system off, use both hands all fingers spread out and gently push the cone in and then let it out and listen and feel for a mechanical sound that might be what you are hearing while playing it.