The Pittsburgh Jazz Festival organized on June 20, 1965 a "Jazz Piano Workshop" which was luckily recorded and issued on CD by Mosaic Records: https://www.discogs.com/Various-The-Jazz-Piano/release/5260834. Here is a picture of the "cast" on that day: https://collection.cmoa.org/objects/cfcdaea2-de64-4f61-92cf-8f4e6d9db60f
Ellington plays two numbers (in addition to a duo with Earl Hines): a spirited version of "Take the A Train", with bass and drum accompaniment, and another piece "