Okay, film mode doesn't do what you think it does.
What film mode does is control how an interlaced signal is deinterlaced. Different deinterlacing strategies are appropriate depending on whether the source material you are watching was originally shot with a film camera or a video camera. The way most TVs work is that if film mode is "off" then the TV assumes that everything it is fed is a video source. If film mode is "on" then it will try and figure out whether it is film or video and adjust accordingly - usually with a bias towards film. (I'm deliberately not going into any technical detail, here).
The upshot of this is that if the original source is actually film then switching film mode on will make it look clearer and sharper, but if the original source is video then switching on film mode will make it look worse. So, if what you're watching is a cinema film, or an american TV series shot on film, you should switch film mode on. If you're watching a low budget UK series or something shot live for TV (like a news broadcast) then switch film mode off.
Differences between PAL and NTSC are relevant if you get into the technical detail of how the TV distinguishes between film and video, and how likely it is to get the decision right (it is much easier to tell the difference between film and video with 60Hz material than it is for 50Hz) but it doesn't directly influence the basic advice: regardless of whether the material is 50Hz or 60Hz, use film mode for film, and not for video.
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