There is, but it is for the executable and supporting library files, not the data files created to store output from the program. So a WMV file is a WMV file regardless of OS.
The ability for an app to use more than 4GB of RAM depends on three things all being present:
1: A 64-bit capable CPU (unless your system is more than about 4-5 years old, this is basically a given)
2: A 64-bit OS
3: A 64-bit app
All three must be present.
I have read about the differences in 32-bit vs 64-bit apps and OS.