You will see an original video and two altered versions, A and B. All three play in a loop.

• Pick the version that is truer to the original — the one you would accept as a faithful copy.
• Anything counts: missing or changed things, blur, blockiness, timing.
• Answer with a click, or with the ← and → keys.
• If you truly cannot tell which is truer, press ↓ — "I can't tell". Use it honestly: some comparisons have an obvious answer.

One round is 40 choices, about 10 minutes. There are no right or wrong answers except a few obvious check questions.

Participation is anonymous and voluntary. We store only your choices, response times, and browser type. By starting you agree to this use.

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