Van Ling didn't do EoD, Kevin Burns did. Someone would have to ask Burns where their footage came from.
Here are some more screenshots of the OOT footage in EoD. The actual 35mm elements must look better than these transfers (or at least they did when these were transferred).
http://imageshack.us/g/502/vlcsnap2011111308h15m21.png/
And here's a comparison of the same shot from two different places in the documentary - the original and the SE:


It's weird how the pre-SE clips look like an old video source, but they can't possibly be, can they? Look at how much more picture there is in the top image. They practically transferred the entire frame - sometimes you can even see the edges. And the fact that there's other footage in EoD (dailies, raw effects passes, etc.) that also has this jaggy, low-res look makes me think that these were transferred at the same time. Also, I don't think that LFL would have an old video transfer lying around with the '77 crawl on it. If they are old video transfers, I'd love to know the circumstances, since these clips do not come from any transfers that were commercially released.
Could the clips from the first film be from George's Technicolor print? The fuzzy, dense look of the '77 footage makes me think of late-80s/early-90s video transfers that were made from IB Technicolor prints. (Ones that immediately come to mind are the Image laserdiscs of the 1937 version of A Star is Born and the Fleischer animated Gulliver's Travels, or the Criterion LDs of Black Narcissus and The Red Shoes.) They had the same high-contrast look, with all the darker areas showing up as murky, and the bright areas being kind of blown out. As has been pointed out time and again on other forums, IB Tech prints do not transfer well to video because of their high contrast and density.
Also, is it just me, or does the Death Star explosion look better than any of the other pre-SE clips? I don't see any jaggies there - and that's the most accurate-looking color I've seen on any official video transfer of the scene. Could that clip be from an entirely different video source than the other clips? Lest we forget, pre-SE footage showed up in the original SE trailer (the original ROTJ DS explosion, as well as the original version of Wedge blowing up the TIE fighter - which only appeared in the first "President's Day weekend" version).
I still insist that LFL is not telling us the whole truth with regards to the condition of the OOT elements. It provides them with a convenient excuse for why they can't release them again.