Not sure how much benefit there is in h265 over h264 or something like j2k at high bitrates, at low rates h265 certainly is beneficial.

Either way 500GB for 2 hours is still significantly compressed - over 90%.

Standard UHD 10 bit 30 bits a pixel, even at just 24fps is 384021603024 = 6gbit/sec just for the video alone without audio, ancillary information, and container overhead. I suspect movies work in 12 bit too, and work at 4k, so that's 409621603624 = 7.7gbit/second, or about 7TB for a 2 hour movie.