Benchmark Almanac

Neptune

Only in system cards

Models answer multiple-choice questions about long videos that need reasoning over many segments.

Gemini 2.5 report uses the test subset, 0-shot, 1,024 frames.

Made by
Google DeepMind
Released
December 2024
Kind
Long videos
Level
Everyday
Scored
Checked automatically
Answers
Multiple choice
Tasks
All public
Strongest model tested
Gemini 2.5 Pro Jun 2025 #96 on the capability index
Last in a system card
July 2025
Last model added
July 2025

In the authors’ words

We introduce Neptune, a benchmark for long video understanding that requires reasoning over long time horizons and across different modalities. Many existing video datasets and models are focused on short clips (10s-30s). While some long video datasets do exist, they can often be solved by powerful image models applied per frame (and often to very few frames) in a video, and are usually manually annotated at high cost. In order to mitigate both these problems, we propose a scalable dataset creation pipeline which leverages large models (VLMs and LLMs), to automatically generate dense, time-aligned video captions, as well as tough question answer decoy sets for video segments (up to 15 minutes in length). Our dataset Neptune covers a broad range of long video reasoning abilities and consists of a subset that emphasizes multimodal reasoning. Since existing metrics for open-ended question answering are either rule-based or may rely on proprietary models, we provide a new open source model-based metric GEM to score open-ended responses on Neptune. Benchmark evaluations reveal that most current open-source long video models perform poorly on Neptune, particularly on questions testing temporal ordering, counting and state changes. Through Neptune, we aim to spur the development of more advanced models capable of understanding long videos. The dataset is available at https://github.com/google-deepmind/neptune

Abstract of Neptune: The Long Orbit to Benchmarking Long Video Understanding (arXiv:2412.09582, CC0)
2
Models scored in lab cards
2
System cards report it, from 1 lab

Gemini 2.5 Pro leads with 87.3%

Best score per model as labs report them in their own cards. Labs pick their own settings, so these compare less cleanly than independent runs.

  1. 1 Gemini 2.5 Pro Jun 2025 87.3%
  2. 2 Gemini 2.5 Flash Jun 2025 84.3%

Source: Labs’ model cards

#ModelScoreSettingDateSource
1 Gemini 2.5 Pro Jun 2025 87.3% Jul 2025 Lab model card
2 Gemini 2.5 Flash Jun 2025 84.3% Jul 2025 Lab model card

Google DeepMind’s own number for Gemini 2.5 Pro passed 85% in July 2025

All the scores we have, one dot each, so a model tested at several settings appears more than once.

Reported by the lab in its model card
0% 20% 40% 60% 80% 100% Near the ceiling (85%) Gemini 2.5 Pro 0% 20% 40% 60% 80% 100% Near the ceiling (85%) Gemini 2.5 Pro

Source: Labs’ model cards

Labs report it only in system cards

We read the headline results of 522 launch posts from 52 labs, and none of them list this benchmark. Some system cards do, below.

2 system cards report it, from 1 lab

Besides launch posts, we read the system cards, model cards and technical reports labs publish with a release. They report far more, including safety and frontier-risk tests.

DateDocumentScoreAs the document writes itSection
Jul 7, 2025 Gemini 2.5 Pro technical report 87.3 Neptune, test, 0-shot, visual + subtitles (Table 6) Capabilities
Jul 7, 2025 Gemini 2.5 Flash technical report 84.3 Neptune, test, 0-shot, visual + subtitles (Table 6) Capabilities

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