...a "film-safe" bag...
No personal experience with "film-safe" bags, but apparently it's a lead-lined bag that blocks X-rays.
Unfortunately, it's suggested on other forums that that the customs official will just turn up the power of the X-ray machine and it could mean that your film is more likely to get damaged.
I've flown to London, Phuket and Macau with ISO 100 and 400 film. So far nothing appears to be damaged.