MediaCoder

Never worked for me

Most videos can only be split on key frames, unless you recode, but I don't know how accurate MC can be without a frame by frame scale.

If MC had used LAVC instead of XVID, it would have told you. LAVC from ffmpeg has the actual fourcc of FMP4. Even if the encode had used LAVC or DIVX (some other app) MPEG4Modifier almost always tells you the REAL codec used regardless of the fourcc. Wheras if you change the fourcc to something else...

So Trim Clip worked once upon a time and Gamma Effects never worked at all.

I have no way of knowing this, but are you sure it really is xvid you are getting and not lavc?

Load in MPEG4Modifier and see what the real codec is.

I bet trim clip worked at least once in the 4000 range

Probably. Almost certainly. FMP4 is not a recognized MPEG4 fourcc for standalones. Just get a fourcc changer and set to XVID or DX50. I seriously doubt there is firmware for anything that acknowledges FMP4 or FFDS. Whether is works from one build to another, it always helps to check the fourcc and f...

A fourcc changer is useful to have for any other files you may come across.

VGA11 used to be under Settings-Overall-Video Options-Pixel Aspect Ratio Mode

No idea where it is now.

If the actual encode is resized, but the player still sees the DAR transferred from the original video, you have to set the DAR to 4:3 and also square pixels = VGA11.