Sorry if I confused the issue. I don't have a problem with file manager. I just want to get rid of it because it comes with 20 language packages and I can't get rid of them selectively

I do have an issue with mplayer integration but that's off-topic in this thread. Stock media player launched automatically by tapping a movie file in file manager. With stock media player gone, nothing launches when I tap the file. I need to open it from mplayer.