MEP 19+ HD? Is this a typo? As far a I know the latest release is 17.
Depending on what you download I think you get an 'installer' which puts things where MEP expects to find them. For most stuff under Win 7 things go by default into 'C:/ProgramData/MAGIX/Movie_Edit_Pro_...' where there are folders for effects, DVD templates etc. For info: under Win XP stuff in usually put into 'Application Data'.