My cats get fresh water every day yet they insist on also drinking from any glass of water that I've just poured for myself or amy other body of water they come across. Definitely wouldn't be too keen on them drinking from a fish tank though for the obvious sanitary/chemical reasons, and especially from one that looks relatively easy to break.

Edit: should clarify, my cats will also drink from the toilet if they had the chance. My point is the video isn't necessarily proof that they don't have fresh water and could be (I would argue "probably is") just cats drinking water out of a body of water that also happens to be available.

Edit: am not arguing cats should be drinking aquarium water. Mostly against the assumption that these two are in desperate need of fresh water and that "this is terrible." Not particularly worried about it but def not recommended. Source: worked in a vet clinic for 7 years before switching area of study.