On Installation the default output location is
C:\Program Files\uRexsoft\uRex Video Converter Platinum\Output
User or even application output data should not be stored under C:\Program Files as this location is reserved for the application software itself, and on some systems, users will not have any file system privileges to write to this folder tree.
Instead use %APPDATA% or %LOCALAPPDATA% for application settings etc and %USERPROFILE% to store the output files with the users documents and files (suggest the "My Videos" folder).