update: Finally, it's on the NASA Johnson YouTube channel! Tennis in Space:
Expedition 56 crew members including NASA astronauts Drew Feustel, Ricky Arnold, and Serena Auñón-Chancellor, and European Space Agency astronaut Alexander Gerst embark upon a tennis match in space aboard the International Space Station.
Commander Drew Feustel commented on the match saying, “Our match in space was pretty challenging due to the fact that we are in a microgravity environment. We did have a net, but the rules allowed the ball to go over or under the net. Also, there was no requirement for us to stay on the ground, so to speak, so we had the freedom to play on the walls, ceiling, or floor. The game space was a bit cramped so we could not really smack the ball without making it unplayable for our opponents. Also, we did not observe a service or base line or any lines for that matter. We just did not have them. We made a lot of modifications, including to the racquets.”
There was a recent and heavily hyped "tennis match in space" as part of a staged event to hype the beginning of the US Open tennis tournament. To make it even weirder, it was projected on the Unisphere in Flushing Meadows, NY, which is incidentally Homer Simpsons's favorite place to go in the greater NY metropolitan area (GIF and Video thereof).
See the US Open page Del Potro Talks Tennis Strategy With An Astronaut In Space where you can see NASA Astronaut A.J. (Drew) Feustel talk with Tennis player Juan M. del Potro.
See also Space.com's Tennis in Space, Anyone? Astronauts Have a Ball During Historic Match and also Astronauts Will Play the First-Ever Tennis Match in Space Tonight! Watch It Live
Here is a screenshot showing Feustel hitting a tennis ball on the ISS being bizarrely projected on the Unisphere: https://i.stack.imgur.com/7IEhI.jpg
Here is another video showing Feustel in an earlier interview, and playing tennis in space!
24:24 he explains some of the physics of trying to play tennis in space in a very thoughtful and informative way. The discussion is too long for me to transcribe right now, I may make an attempt later if I have more time.