From the official website is a preview clip for media folks:

http://www.loc.gov/today/pr/2010/10-273.html

follow the pressroom link:

You will be asked to create an account, fake it, they'll e-mail you a password (don't laugh at the password...), return to the announcement page:

http://www.loc.gov/pressroom/kits/name/The-2010-National-Film-Registry

Scroll down to:

The Empire Strikes Back
The Empire Strikes Back (1980) Courtesy of CBS/Fox

Yoda teaches Luke Skywalker (Mark Hamill) how to be a Jedi knight.
[Preview | Download 31.96 mb]

So first thing to note is 'Courtesy of CBS/Fox' maybe they're keeping the VHS, but this will answer the 'where'd they get this version question'. I'll leave it to the better color educated, but they don't look DVDish, but the colors could be as they are because of the high compression for this clip, it's weird that it's pan/scan. But again, this could be a media clip offered from CBS/Fox's press corps not Lucasfilm or a digitization of the actual film going into the archives.