Am looking at the even better copy of the video on YouTube.
Stopping at the up-close frames of the gin, looks to me like it was NOT sealed. There’s a shiny gap between the plastic top and the plastic collar that holds the top to the bottle until the seal is broken. That “shiny” usually isn’t visible until the seal is broken. An “open container” conviction carries a maximum penalty of a $150 fine.
That the driver had an open bottle of gin at his feet just adds to his escalating list of offenses during the stop and raised the stress level for both, as its easy access and awkward concealment start pointing to drinking _while_ driving. Consumption of alcohol in a motor vehicle is a fourth-degree misdemeanor with maximum penalties of 30 days imprisonment or a $250 fine or both.
For what it's worth (and I don't think it is really relevant to the ultimate issue of whether the shooting was justified), after another look at the video, you are 100% correct that the bottle had been opened. But the reason is even more simple than a gap between the cap and the seal. Here is a screenshot of the bottle:
And here is picture of a bottle of Barton Gin:
Notice anything?
Whatever was in that bottle, it wasn't gin (well, at least it wasn't Barton Gin).