Unfortunately plugging all devices into a common power bar will not really help, as with two-prong plugs you can simply rotate the plug 180 degrees, and switch the "hot" and "cold" wires to the plugged in device, meaning that there can still be a huge voltage difference between one device's chassis, and the other devices's chassis.
you really need at least one device plugged in with a three-prong plug, into a grounded outlet, so the leakage current can flow to ground safely.
and yes, I totally agree that the "ground point" you are connecting the TV's chassis to should be a reliable connection to ground, It would be horrible if you try to use a metal gas pipe, with an incomplete connection to ground, an electric spark and gas isn't a safe combination
. Use common sense!
here is a site that explains the problem, with an easy to understand picture:
https://www.meanwelldirect.co.uk/glossa ... e-current/
L = Live and N=Neutral if E (Earth) is not connected, the leakage current flowing through the 2n2 capacitors connected to L will flow into the chassis (dotted line) which is connected to the GND of the device, instead of flowing to earth through the E wire.