This is a partial answer I found while researching the question.
Ramsey Orta, who shot the video, reported to the NY Daily News that he was invited to discuss the video with the grand jury - and that they did show the video.
It's not clear if this is the first or only time the jurors saw the video, and it's also not made certain that the whole video was shown. He doesn't mention precisely which parts were shown, and he suggested that his discussion of the video was cut short:
“They actually cut my time short,” Orta said. “My lawyer told me I was
supposed to be in there for at least a half an hour and I only stayed
maybe 10 minutes.”
He does mention his surprise that the jurors asked no questions about the police actions or how Garner died, but instead focused on the very start - on what Garner (and Orta) had been doing before the police approached:
"The whole thing was just about Eric — why was he selling cigarettes,
did you know he was selling cigarettes?"
“What was Eric doing there? Why was Eric there? Nothing pertaining to the cop choking him,”
"One grand juror asked me, ‘If you knew he was selling cigarettes, why didn’t you tell him the cops was there?’"
“Maybe three [jurors asked questions], that’s all. The rest of them, they weren’t even worried about nothing.”
So, this is evidence that at least some of the video was shown - but it does leave two things unknown:
- It's not certain from this alone that the whole video was shown
- It's not certain that the video was ever presented as being evidence of how Mr Garner died. Orta's account would also fit the video being presented only in the context of some other element of the case, such as the reasons for Garner being initially approached by the police.