Niconico Video Downloader
Save any ニコニコ動画 video as a plain MP4 — the danmaku comment layer stays out of the picture unless you want it.
Why download Niconico videos with ViralMint?
Niconico's signature feature is its danmaku comment layer — thousands of viewer comments scrolling across the frame — and that layer is the thing most downloaders get wrong. The comments are not part of the video: they live in a separate XML timeline the player composites at playback, so a proper download returns clean footage and leaves the commentary behind. ViralMint uses yt-dlp locally, which pulls the source stream directly rather than screen-capturing the player, so you get the original encode with no overlay and no re-compression. Higher-quality streams and some member-only uploads need a logged-in session; ViralMint reads your browser cookies for those the same way it does for age-gated YouTube. Niconico caps most public uploads at 1080p, and long archived streams download in one pass rather than the segment-at-a-time approach browser tools fall back to.
How to download from Niconico
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Copy the Niconico video URL
From nicovideo.jp, copy the share or page URL — e.g.
https://www.nicovideo.jp/watch/sm40000000 -
Paste it into ViralMint
Open the ViralMint desktop app and paste the URL into chat. The planner detects the Niconico URL and triggers the download automatically — no flags, no command line.
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Get the mp4, transcript and AI insights
The video lands in the Videos page with a local Whisper transcript and AI-extracted hook / structure / tone — ready for clip extraction or repurposing.
Frequently Asked Questions
Will the scrolling comments be burned into the file?
No. Niconico serves the danmaku as a separate comment timeline that the web player draws on top at playback time, so a stream-level download returns the clean video. That is also why you cannot get the comments back by downloading harder — if you want them, they have to be fetched and rendered separately.
Do I need a Niconico account?
Not for ordinary public videos. You do for member-only uploads and for the highest-quality streams on some videos, since Niconico gates those behind a logged-in session. ViralMint can use your browser's existing cookies, so signing in once in your normal browser is enough.
Can I download an archived live stream?
Yes, where the archive is still public and within its retention window. Niconico expires many live archives, and no downloader can recover one after the platform has removed it — grab it while it is up.
How ViralMint compares to other Niconico downloaders
| Approach | Examples | Trade-off | ViralMint advantage |
|---|---|---|---|
| Online converters | Y2mate, SaveFrom, ssyoutube, OnlineVideoConverter | Pop-up ads, redirects, quality capped at 720p, file-size limits, no batch downloads, your URL logged to ad networks | Local app, zero ads, original quality (up to Up to 1080p (source dependent)), unlimited file size, batch mode |
| Browser extensions | Video DownloadHelper, FastestTube, similar Chrome / Firefox add-ons | Routinely broken after Niconico updates, removed from stores for ToS violations, no transcript or AI analysis | Updates with yt-dlp upstream (community-maintained), independent of browser extension stores, Whisper transcript built in |
| yt-dlp command line | yt-dlp, youtube-dl | Most flexible option but requires terminal comfort, manual cookie handling, no GUI for batch selection | Same yt-dlp under the hood, wrapped in a desktop GUI with cookie auto-detect, batch UI, and post-processing pipeline |
| Closed-source desktop apps | 4K Video Downloader, Allavsoft, ByClick Downloader | Closed-source, paid tiers gate batch and HD, no AI pipeline, no extensible Whisper / FFmpeg post-processing | Open source (AGPL-3.0), AI features prepaid per-action, integrates with the rest of the ViralMint creator pipeline |
Supported URL Example
https://www.nicovideo.jp/watch/sm40000000Equivalent yt-dlp command
If you already use yt-dlp, the desktop app's Niconico download is equivalent to running:
yt-dlp -f "bv*+ba/b" --merge-output-format mp4 "https://www.nicovideo.jp/watch/sm40000000"ViralMint also auto-runs Whisper transcription, downloads the thumbnail, and extracts AI hook / structure / tone insights — steps that take a separate command chain in raw yt-dlp.