Hi lebb again welcome :flower:
SJ is right,I am one those who, once I learned how to use it, have had satisfactory results.
if you want to compress a 50 to 25, you will need to go to common settings,
DVD/Blu-ray / Write / blu-ray / Writable media(BD50) Size / drop down grab size 47732 / OK
Left column / Blu-ray to Blu-ray / default size output / drop down size BD 25 1080P / check Always remove HD audio / OK
Left column / General / GPU acceleration / disable GPU acceleration / close common settings.
under blu-ray to blu-ray / chose main Movie / when video opens remove all subs that you don't want, on the quality tab choose BD25 1080P, a scan will start, let scan complete, hit start, then find something to do, cause this will take a little while to complete.
if you need more assistance you know where to find us.
hope this helps