I don't understand the desire for a blu-ray level 50gb file; you most likely won't be able to notice the difference! Most films on a BD50 only take up 25 to 35 GB on the disc after special features and aux audio tracks...

If you're going to spend the time and resources to create that big of a file, why not make actual use of the extra space and create something that exceeds blu-ray (circa 2008)? Hell, create a 264 encode with 2K resolution that uses P3 color space @ 4:2:2, 10 bit, and you have a file that'd be worth downloading due to it looking better than any Blu-Ray.