[surye]

The claim is not that every output has a unique input, which would not be correct, and seems to be what you are addressing.

[chias]

at 1:08 in the video, that is exactly what he claims:

"So every piece of data in the world has its own unique hash digest."

This is false for the reasons apeescape describes: every piece of data in the world has its own hash digest, but these hash digests are not unique.

[infogulch]

Yes that sentence is technically incorrect, but practically correct. We've never found a collision and though we expect it to be theoretically possible, even common if you consider "all possible inputs" and the pigeonhole principle, for practical purposes hash outputs are unique because nobody considers "all possible inputs" when evaluating probabilities.

I'm saying that for a layman explanation, it's reasonable to say that hash outputs are unique. Because following that with "technically, it's more 'practically' unique, theoretically there are collisions but you won't encounter them with probability > 2^-256" (or whatever it is) just confuses the topic to them more than just summarizing. You have to admit that most people won't go on a 200h adventure to learn about the state space of 256+ bits and how to conceptualize tiny statistical probabilities, so there must be a point where you have to cut the explanation to an approximation of the truth. This is true in every field.

[ChristianBundy]

On the other hand, if we can count "every piece of data in the world" then we can estimate the probability of having a collision.

[riquito]

I see what you mean, but it sounds like the output is unique, and we probably agree that in this field you need to use sentences that cannot be easily misinterpreted.