You have to open and check those low voltage gray connectors too, not just the HV--it could be anywhere.
The 12V should be disconnected while doing this also.
There was a black wire with a crimped ring terminal to a rusty stud near the end of the video. That is likely a chassis ground connection. i would recommend to inspect that closely and maybe measure the resistance from the stud to chassis, then brush and clean off the rust and renew all the contact surfaces of the terminal. This is dicey if the rust has frozen the nut and it will need penetrant lube to free it up, and the stud could break while trying to remove the nut. So evaluate the risk before acting.
Find the other end of the black wire and inspect that termination also.
Pull up the rear seat cushion and inspect all the wiring and connectors under there, looking for rodent damage and corrosion, etc.
The 12V should be disconnected while doing this also.
There was a black wire with a crimped ring terminal to a rusty stud near the end of the video. That is likely a chassis ground connection. i would recommend to inspect that closely and maybe measure the resistance from the stud to chassis, then brush and clean off the rust and renew all the contact surfaces of the terminal. This is dicey if the rust has frozen the nut and it will need penetrant lube to free it up, and the stud could break while trying to remove the nut. So evaluate the risk before acting.
Find the other end of the black wire and inspect that termination also.
Pull up the rear seat cushion and inspect all the wiring and connectors under there, looking for rodent damage and corrosion, etc.