Best AI Video Summarizer Chrome Extensions in 2026
A hands-on look at the AI summarizer extensions people actually install — what each one covers, where each one stops, and how to pick.
Mentorina#comparison#youtube#chrome-extension
"AI summarizer extension" covers at least three different products that happen to share a category name. Some summarize YouTube and nothing else. Some are general-purpose AI sidebars that treat video as one feature among thirty. Some only work on one streaming service. Picking the wrong kind is the most common way people end up with two extensions doing half a job each.
This is a map of the space, not a ranking. What matters is which shape fits how you actually read and watch.
The three shapes
Focused video summarizers. Eightify, summarize.tech, Coursnap, Video Highlight. They do one thing — turn a YouTube video into timestamped key points — and they do it well. If YouTube is 95% of what you need summarized, a focused tool will usually feel better than a generalist.
General-purpose AI sidebars. HARPA AI, Sider, Monica, Merlin. These are chat assistants that live in a panel and can do a lot: rewrite an email, explain a page, translate, run prompts. Video summarization is in there, but it is one entry on a long feature list, and it usually shows.
Single-service tools. Extensions built only for Netflix, or only for PDFs. Narrow by design. They tend to handle their one service carefully — for example, several Netflix summarizers correctly stop at your current playback position — but they do not follow you off that site.
What each shape covers
| YouTube | Netflix | PDFs | Web pages | |
|---|---|---|---|---|
| Focused video summarizers | Yes | No | No | No |
| General AI sidebars | Yes | No | Sometimes | Yes |
| Netflix-only tools | No | Yes | No | No |
| Mentorina | Yes | Yes | Yes | Yes |
Checked August 2026. Feature lists move; check the store listing before you decide.
The gap in that table is the reason Mentorina exists. Nothing stops you from installing a focused YouTube summarizer plus a Netflix tool plus a PDF reader — plenty of people do. It just means three panels, three subscriptions, and three places your chat history lives.
Things worth checking before you install anything
Does it need the transcript, and what happens when there isn't one? Every YouTube summarizer works from captions. A video with no captions at all cannot be summarized by any of them, regardless of what the marketing says. Auto-generated captions count. Tools differ in whether they tell you clearly or fail silently.
Does it upload your file, or read it in place? PDF tools split hard here. Some want you to upload the document to their site. Others read what is already open in your browser tab. If the document is a contract or something from work, that distinction matters more than the summary quality.
Does the summary know where you are in the video? For a tutorial it is irrelevant. For a series you are three episodes into, it is the whole thing. Tools that summarize the entire episode will happily tell you the ending.
Where does the chat history go? Most of these tools let you ask follow-up questions. Fewer of them remember the conversation when you come back to the same page tomorrow.
How to pick
If you only summarize YouTube, install a focused tool and stop reading.
If you already pay for a general AI assistant and video is occasional, use the one you have. The video feature will be adequate.
If you switch between watching, reading and skimming documents in the same afternoon — a lecture, then a PDF, then an article — the split between "video tool" and "reading tool" is the thing costing you time, not the quality of any individual summary.
That is the case Mentorina is built for: one panel, on whatever is open, with the video summary cut at your playback position so nothing ahead of you gets spoiled.