modulator

[Electronic M]

I can't see a problem in the video....

If the over modulation lights stay lit with the controls all the way down, then that is a problem with hum (probably 60Hz) getting into the signal. It could be a result of your AV source having a different ground voltage than the modulator, or mod output being connected to something with a different ground potential. Using a power line isolation transformer to power things independently may work to fix it. You can trace the source by unplugging things till the lights go out.

My agile mod likes to randomly introduce hum in it's output, and interfere with my fixed modulators....Some BT modulators are old enough that the lytics have gone bad, and I suspect mine is one....Yours could also be one.