Billy Williams Day, a doubleheader from June 29, 1969, is a topic that has been discussed on numerous occasions. Three years ago, we saw a brief clip of the final out of Game 1 from that double header at Wrigley. Our original post back in 2012 focused on color video tape footage from the 8th inning of that first game.
The description of the events of that clip were:
The clip seen here is of Ernie Banks driving in the 1st run of the game with an RBI single up the middle. This clip, as well as the other Gibson shots, come from Revisiting the 1969 Cubs , a WGN produced clip that (judging by onscreen graphics) was put together in the 1990's.On January 31, 2017, MLB.com uploaded an extended video clip of Banks' single off of Gibson in the 8th inning. This clip can be found on their YouTube channel. The footage is color videotape and is complete with the Jack Brickhouse call.
Without speaking to MLB, the source of this clip most likely comes from the WGN highlight reels that were compiled throughout the season. Many of these survived from the late 60's and early 70's. They often times represent the only broadcast footage that remains from WGN.