As people have said it doesn't compound, because stable orbits are stable. If it slows it down which means the opposite side of the orbit might change by like 50m closer to the sun, as he said negligable but that doesn't mean it starts spiralling towards the sun at 50m per year because as it falls closer to the sun it also gains speed, which causes it to fly back out again to the original distance when it gets back to the same point in it's orbit. The orbit is still stable, simply elliptical (which the earths orbit already is by significantly more than 50m).