Switching to PAL will not clear up inter modulation distortion, it just make the image a bit larger in the view finder I should have mentioned that.
The lines are due to a standing wave at harmonic of 60hz, switching to 50hz makes them farther apart, but will not correct the problem. Placing a terminating load resistor 75ohm may help. I hope it is not the video output circuits in the thermal that would suck. The outdoor mode just gives a little more contrast for me in the open fields. The pal mode makes the viewfinder screen a bit larger which gives a bit more magnification.