rtve.es has posted a very short video of Rafa just after a practice session.
Google translates the page text:
Rafa Nadal tiene buenas sensaciones de car a la próxima temporda y está entrenando a tope, alejado ya de las lesiones
Rafa Nadal has a good feeling about the next car temporda and is training hard, and away from injuries
A longer video with practice footage has been uploaded to YouTube by vamosrafelnadal:
YouTuber mer930 posted a translation:
Rafa said: “With much hope, as always — the season has ended late this year but I’m well now, I’ve trained a lot during this short time I’ve had, and now with the hope of beginning this season and trying to do as well as possible from the beginning.”