Hello everyone, I know this is an old and very underrated game, but does anyone know if there's a way to de-interlacing (aka "removing the scanlines") from the FMVs?

And there are subtitles in this game?

Unfortunately, no and no:
1) on FMV's, it's part of the compression technology they used, no way the quality can be improved.
2) no subtitles option

But, you can improve on all the general graphics of the game, use the graphic configurator before launching the game (that's a separate program than the game launcher, look in the start menu), and choose a high quality interpolation driver, as well as a high resolution setting, you'll see the quality going relatively up thanks to a finer scaling.

www.gog.com/forum/phantasmagoria_series/workaround_for_black_scanlines_in_phantasmagoria_2
this method works for me on spycraft

It still works, thanks