So will it work if I were to install a Euro FW on my US PS3 to get this option?
As idone says, there's only one firmware that covers all regions of PS3. The region code (for games, and for Blu-ray movies) is held outside of firmware, and is not changeable.
With regards to Blu-ray movies at 50Hz, note that PS3 HDMI output is either 60Hz, or - if your display supports it - 24Hz. Most (all?) Blu-ray movies are encoded at 24Hz, irrespective of whether they are Region A or B.
If your display doesn't support 24Hz playback, then regardless of your actual region (US/Europe/other) there'll always be some kind of pull-down/up to convert from 24Hz to the display rate (50Hz, or 60Hz).
Hope this helps,
p.s. There's a 'Play videos at 50Hz is available' option in newer PS3 firmware, but I believe that's really to allow for videos exported from PlayTV (which, in Europe, are at 50Hz in Standard Definition) to play without any kind of conversion.
If you're being prevented from playing a different region Blu-ray movie on your PS3 (eg: a European Blu-ray that is locked to Region B, on a US PS3), then that would be down to region coding. Blu-ray movies aren't encoded at 50Hz or 60Hz, and not all Blu-ray movies are region free, unfortunately.
You shouldn't need to go buy a TV that supports Blu-ray playback at 24Hz (it makes a reasonable difference, but it's not required.. my previous TV didn't support it, and I was able to play back US-authored region-free Blu-ray movies on my EU PS3 via HDMI without problems).
I guess further questions to narrow down your problem would be:
a: What is the Blu-ray you're trying to play?
b: How is your US PS3 connected up to your TV?
c: What TV is it?
Have a read of this : http://forum.blu-ray.com/showthread.php?p=1377549
According to that thread, that particular Blu-ray is encoded at 1080i/50Hz (it's not 1080p, regardless of what the box might say).
There's no way you can enable 50Hz video mode output on a US PS3, so your only chance of playing it on your US PS3 (short of getting a new TV that supports 50Hz too, and hoping that the US PS3 will output it - which isn't guaranteed) is to rip it from the Blu-ray disk (on a PC BD-ROM drive using http://www.slysoft.com/en/anydvdhd.html), and turn it into a standalone video file.
ArniePie, really appreciate all your help, very much appreciated.
Think its not going to work so will put it down to experience.
My TV does actually support 50hz, so its the PS3 I believe where the issue lies. Ah well. I believe changing to component cables (rather than HDMI) may get it at 50hz, but as the BluRay is at 1080i only, I guess this wont change anything for the better anyway.