Which YouTube summarizers need captions?
Most tools read the caption file YouTube already has. If a video doesn't have one, they either refuse the link or hand back nothing, so it's worth checking which camp a tool is in before you sign up.
Why a video ends up with no captions
Auto-captions don't always show up. Music-heavy audio, some languages, and very fresh uploads are the usual gaps. Creators hit this on their own back-catalog more than anywhere else, and it's the one case where a summarizer has to make its own transcript from the audio.
Quick check: open the video on YouTube and look for the CC button or "Show transcript" under the description. Nothing there means no caption file.
What each tool needs
| YouTube Collector | NotebookLM | NoteGPT | |
|---|---|---|---|
| Needs an existing caption file | No. Makes an AI transcript from the audio (credits-billed, first 2 free) | Yes. "Only public YouTube videos with captions, either user-uploaded or auto-generated, are supported" | Says no. Its page claims videos up to 150 minutes "even if they have no subtitles" |
| Bulk playlist or channel import | Yes, paste one playlist or channel URL (Pro and Creator) | Not documented. Sources go in one at a time | Not checked |
| Summaries with clickable timecodes | Yes, chapters that seek the in-app player | Imports the video's text transcript only; no chapter outline that jumps the player | Not checked |
| One search across everything you've saved | Yes, titles, summaries and full transcript text | Not documented | Not checked |
| Repurpose a video into a blog post, thread or LinkedIn post | Yes | Not documented | Not checked |
| Searchable community transcript cache | Yes | Not documented | Not checked |
"Not checked" means we didn't confirm it against their own site, not that the answer is no.
Where the other tools sit
Eightify and summarize.tech both returned errors when we tried to load their pages on 28 July 2026, so we're not making claims about what they do or don't need. Check their sites yourself before you buy.
Choose the other one if
Choose NotebookLM if your videos already have captions and most of your sources are documents anyway. It's free, it handles long videos (no length cap until the caption file passes 500,000 words), and cross-source Q&A is its strength.
Choose NoteGPT if you want a one-off summary and don't need a library you can search later.
Choose YouTube Collector if you're working through a back-catalog or a playlist, some of it uncaptioned, and you want everything in one searchable place afterwards.
FAQ
Does a fresh upload work? On NotebookLM, not always. Its docs say videos uploaded less than 72 hours ago may not be importable, because the captions aren't ready. Transcribing the audio sidesteps that wait.
What does the AI transcript cost here? Credits, and the first two are free. Videos that already have captions don't use credits.
How good is it on rough audio? Noisy rooms, heavy accents and crosstalk come out worse than clean speech. That's true of every speech model, ours included.
What about a video with no talking at all? Nothing useful comes out, and NotebookLM's docs rule those out too.
Try it on the video that failed
Pick the one video that got rejected somewhere else and paste the link. You'll get the transcript, a time-stamped summary and chapters that jump to the moment. Free tier, no card.