Caveat: I am not a programmer, just an enthusiast. Windows programs typically package all of the dependency libraries up with each individual program in the form of DLLs (dynamic link library). If two programs both require the same dependency they just both have a local copy in their directory.
worth mentioning that any intel cpu with an iGPU from generation 7 (kaby lake) and up can handle 4k hevc transcode in hardware. i just upgraded my plex box to an i7 8700K and it works quite well. an old office workstation with like a 9th or 11th gen intel cpu would probably rip through transcodes.