Why do you need licenses for pi3 pi4? Mine work fine without. Only needed in the Dark Ages of pi1b maybe pi2 (don't recall on pi2 didn't have one).
Something wrong with hardware decoding?
I think it's fine for SD MPEG2 interlaced content - but decent deinterlacing of HD MPEG2 on a 3B may be pushing it. 4B will be fine I think (which is why they don't include an MPEG2 licence option for the 4B)