obviously multi-walled annular voids of varying volume WITHIN the individual glasses. pour the liquid into ever thinner rings to make it look like it's filling the whole glass volume. really, I hope if aliens exist they don't see this. I mean really, it's a little embarrasing for our species to still be fooling itself so easily in these ways!

I'm thinking a partition. (the "multi-walled annular voids" seems to comples)

One wall along the diagonal with angled walls to reduce volume.

when he fills the large glass you can see the top of a column inside the glass as the liquid nears the top.

*discard

Self-discarding this video (discard called by original submitter eric3579)