" Of all the time spent on the lunar surface, this arguably is the strongest evidence that they were in a vacuum."

I would think that the 800lbs of rocks and soil samples would be the strongest evidence, but yes to people who dont have the positions necessary to actually handle moon samples, the strongest evidence is the videos, and them being shot in 1/6th G and vacuum.

"What experiments could they have done to show that they were in a vaccuum?"

No experiments necessary, they walked, hopped, and drove the rover enough times to show us that the soil acts as if in 1/6th G and vacuum.


"my brother explained this away by telling me their boots were lined with lead"

And now do you know a better reason? I do.