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    "headline": "The Video Critic Stopped Rewarding Stillness",
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    "dek": "A 4D reconstruction reward modeled scene dynamics instead of treating motion as geometric error.",
    "summary": "A 4D reconstruction reward modeled scene dynamics instead of treating motion as geometric error.",
    "body_text": "Streaming video generators can learn to freeze because a rigid 3D consistency critic penalizes genuine object motion. Stream4D replaces that critic with feed-forward 4D reconstruction, adds a motion prior and retains a perceptual anchor. Across tested autoregressive backbones and horizons, the authors report better 4D reconstruction, motion retention and human-aligned preference. The abstract does not claim removal of every long-horizon artifact.",
    "why_it_matters": "A 4D reconstruction reward modeled scene dynamics instead of treating motion as geometric error.",
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      "The abstract does not claim removal of every long-horizon artifact."
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        "qualification": "The abstract does not claim removal of every long-horizon artifact."
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    "tags": [
      "video generation",
      "diffusion models",
      "4D reconstruction"
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    {
      "source_id": "source-2026-08-22-014",
      "title": "arXiv preprint 2608.19556",
      "publisher": "arXiv",
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    "title": "The Video Critic Stopped Rewarding Stillness",
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