Gemini 3.8 Flash Video Agent

Gemini 3.8 Flash Video Agent (Video Understanding LLM)

What is Gemini 3.8 Flash Video Agent?

Gemini 3.8 Flash Video Agent is a video understanding model that answers questions about a video and returns text, usually with precise MM:SS timestamps. You give it a direct video URL, an uploaded file, or a public YouTube link plus a question, and it replies in plain language.

It runs Gemini's agentic video understanding. Instead of statically sampling every frame at one frame per second, the model reads your prompt first, then dynamically navigates the timeline, loading only the frames, audio, and transcript it needs to answer. That makes it fast and economical on long footage, where the answer often lives in a few moments buried inside hours of video.

Key Features

• •Agentic timeline navigation that targets the moments relevant to your prompt.
• •Long-video support, from 10-minute how-to clips to 90-minute lectures and multi-hour recordings.
• •Direct video URLs, uploaded files, and public YouTube links as input.
• •Answers that cite exact MM:SS timestamps and can read on-screen text.
• •A medium or high reasoning effort control to trade depth against token cost.

Best Use Cases

• •Needle-in-a-haystack search: find a specific moment, quote, or event and get its timestamp.
• •Sub-second moment retrieval and cut-boundary detection for automated video editing.
• •Content indexing, chapter markers, and media search across archives.
• •Anomaly and state-change detection in monitoring, lab, or industrial footage.
• •Counting repeated actions or distinct objects over time in sports or process video.
• •Q&A and summaries over meetings, lectures, tutorials, and conference talks.

Prompt Tips and Output Quality

Ask a targeted question about a specific moment and request the timestamp, for example at what point the solution turns blue or when the pricing slide appears. In testing on a multi-scene lab clip it returned the exact moment (00:20 to 00:24), named the following scene, and read the on-screen numbers correctly. Use effort: high for long videos and fine moments; medium is faster for simple asks.

How to Use Gemini 3.8 Flash Video Agent

Gemini 3.8 Flash Video Agent turns a video into answers. Send two things, a video and a prompt, and read the text reply. The video can be a direct URL, an uploaded MP4, WebM, or MOV up to 2GB, or a public YouTube link, and multi-hour videos are supported. Place a clear question in prompt and the model navigates the timeline to find the answer.

Get the best results

• •Ask about one thing at a time. Target a specific moment, person, object, or claim rather than requesting a full transcript.
• •Request a timestamp. Phrasing like "at what timestamp" steers the model to search the timeline and cite an exact MM:SS point.
• •Lean on long videos. Agentic navigation helps most on lectures, meetings, tutorials, and recordings where the answer sits in a few moments.
• •For counting or rapid motion, say so ("how many times does X happen"), which prompts the model to rescan the relevant window.

Recommended Settings

• •effort: high (the default) for long videos, precise moments, counting, and anomaly detection. It reasons more thoroughly and is billed as output tokens.
• •effort: medium for short clips or simple summary questions where speed and lower cost matter.
• •Keep prompts specific; put the single most important question first.

Example prompt tested end to end

This example ran end to end at the settings shown; the length, scene order, and on-screen detail all carried through.

• •Find a moment and its timestamp. Prompt: "A chemist runs several steps in this lab session. At what timestamp does the solution in the flask become bright cobalt-blue, and what does the chemist do in the scene immediately after?" On a 40-second, multi-scene lab video the model returned the exact window (00:20 to 00:24), correctly named the next scene, and even read the trial numbers written on the board. Tip: name a distinctive visual cue (a color, an object, a slide) so the model has a clear target to search for.

More prompts to try

Use these as starting points, adapting the cue to your footage:

• •"How many times does the player shoot in this clip? List each timestamp."
• •"At what point does the presenter show the pricing slide?"
• •"Describe any unusual or unexpected event and give its time window."
• •"Summarize the three main arguments, with a timestamp for each."

Does it accept YouTube links?

Yes, public videos, plus direct URLs and uploaded files.

How long can videos be?

Several hours; long content is where agentic navigation helps most.

Does it return timestamps?

Yes, in MM:SS format.

Does it generate video?

No. It analyzes and answers; it creates no footage.

What does effort change?

How thoroughly the model searches. Higher effort reasons more and is billed as output tokens.