What J&F accuracy does the SAM 2 paper report for video object segmentation, where does it say SAM 2 fails, which checkpoint does the public README actually describe, and what licence covers each component?

Paper v2 reports SAM 2 (Hiera-B+) J&F of 76.6 on MOSE val, 90.2 on DAVIS 2017 val, 78.0 on LVOS val and about 77 on SA-V val/test, ahead of Cutie-base+ (71.7, 88.1, -, 61.3/62.8) when prompted with the first-frame ground-truth mask. The authors list failures: shot changes, crowded scenes, long occlusions, extended videos, and thin or fine details when fast-moving; they recommend refinement clicks on later frames. The public README's SAM 2.1 per-checkpoint numbers (large: SA-V test 79.5, MOSE val 74.6) match the paper's appendix rows marked as trained without the VOS datasets, not the headline row (MOSE 77.9), which is a documented difference an agent must not collapse. Licences: checkpoints, demo and training code Apache-2.0 (README), SA-V dataset CC BY 4.0 (paper), a third-party connected-components file carries its own licence. Curator qualifications: Verified all numbers and the 77.9-vs-74.6 MOSE difference (training mixture per Table 17 caption; downloadable checkpoint mixture unstated). Rights by component: code and checkpoints Apache-2.0 per README, fonts OFL, cc_torch own licence, SA-V CC BY 4.0. These are separate components, so no conflict. Rights/verification notes are shown as limitations (L00 0019/ADR-0011): they restrict reuse of the cited material or record what was not verified; they are not cleared by this summary. Limitations: [component_reuse_restriction] SA-V underlying video rights not discussed. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

{
  "citations": [
    {
      "url": "https://arxiv.org/abs/2408.00714v2",
      "note": "Table 6; Table 17; limitations; release sentence; SAM 2.1 table; License"
    },
    {
      "url": "https://github.com/facebookresearch/sam2/blob/2b90b9f5ceec907a1c18123530e92e794ad901a4/README.md",
      "note": "Table 6; Table 17; limitations; release sentence; SAM 2.1 table; License"
    },
    {
      "url": "https://github.com/facebookresearch/sam2/blob/2b90b9f5ceec907a1c18123530e92e794ad901a4/checkpoints/download_ckpts.sh",
      "note": "Table 6; Table 17; limitations; release sentence; SAM 2.1 table; License"
    },
    {
      "url": "https://github.com/facebookresearch/sam2/blob/2b90b9f5ceec907a1c18123530e92e794ad901a4/LICENSE_cctorch",
      "note": "Table 6; Table 17; limitations; release sentence; SAM 2.1 table; License"
    }
  ]
}