You do not need to sit through a 40-minute video to find the five minutes that matter. Google's Gemini can read a public YouTube video from its link and summarise it. This post gives you the exact prompts to use, a second method for very long videos, and the honest limits.
What you need
A Google account and the Gemini app (web or mobile). The free version works.
Gemini Apps Activity turned on. Google's help page says the YouTube feature is not available when this setting is off.
The link of a public YouTube video. Copy it from the Share button on YouTube.
Optional, for very long videos or deeper analysis: Google AI Studio, free with a Google account.
Step by step
Open Gemini at gemini.google.com or in the app, and start a new chat. Make sure you are signed in.
Paste the link and the main prompt. Replace the brackets:
Summarise this YouTube video: [paste link]
Give me:
1. A 3-line summary of the whole video.
2. The key points in order, each with a timestamp (MM:SS) so I can jump to it.
3. Any numbers, tools, names or resources mentioned, as a list.
4. The 3 most useful, actionable takeaways for someone who [your situation, e.g. is a beginner learning Excel].
5. Anything the speaker says that is an opinion or a claim I should double-check.
Only use what is said or shown in the video. If something is unclear, say so instead of guessing.Ask follow-up questions. Gemini keeps the video in the chat, so you can dig in:
What exactly does the speaker say about [topic]? Quote the relevant part and give the timestamp.Turn this video into a step-by-step checklist I can follow, with the timestamp for each step.Make 5 quiz questions with answers from this video so I can test myself.For a quick version, use this short prompt:
[paste link]
Summarise this video in 5 bullet points with timestamps, then tell me in one line whether it's worth watching in full for [your goal].For very long videos or detailed analysis, use Google AI Studio. Open AI Studio, start a new chat, add the YouTube link (or paste it in your prompt) and use the main prompt above. Google's developer docs say models with a 1 million token context can handle up to about 3 hours of video at low resolution, or about 1 hour at high resolution. On the free tier you can process up to 8 hours of YouTube video per day.
Check before you rely on it. Click two or three timestamps to make sure they match what Gemini said. Timestamps and quotes are where AI summaries most often slip.
Good to know
Public videos only. Google's developer docs say private and unlisted videos are not supported. Age-restricted or region-locked videos may also fail.
Length limits. Google does not publish a fixed length limit for the Gemini app. Long videos usually work, but for 2-3 hour videos AI Studio is more reliable.
How it "watches". In the developer API, Gemini samples about one frame per second and also processes the audio. Fast visual details, like code on screen for half a second, can be missed. Ask it to describe a specific moment if that matters.
Accuracy. Summaries can miss nuance or mix up who said what. For study notes, exams or anything you will quote, check the original.
Privacy. With Gemini Apps Activity on, your chats may be saved to your Google account and, depending on your settings, reviewed to improve Google's services. Do not paste anything private into the chat.
Respect the creator. Use summaries for your own learning. Do not repost someone's video content as your own.
Sources
Gemini Apps Help: Find and ask about YouTube videos in Gemini
Tom's Guide: How to use Google Gemini to summarise a YouTube video
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