That is because the background in v2.0 is a still image from the SE. Also, the compression in the clip hides some of the grain in the cleaned up v2.5 version, of which there's actually plenty.
Plus I really don't see where any parts of the probe have "become thinner" in the filtered version.
Whereas in the v2.0, they certainly were thinner because of the way the probe and the smoke were composited from GOUT onto the SE HD background:
Thanks for the GIFs, g-force :-)