Nicovideo Downloader
Track SERP’s in-development NicoVideo browser extension scope and waitlist positioning before release.
Overview
nicovideo-downloader is an agent skill for the Build phase that describes SERP’s upcoming NicoVideo browser extension for saving nicovideo.jp playback as local MP4 files (not yet released).
Install
npx skills add https://github.com/serpdownloaders/skills --skill nicovideo-downloaderWhat is this skill?
- Upcoming Chrome/Edge/Brave/Opera/Firefox extension focused on classic nicovideo.jp playback pages
- Planned in-browser MP4 capture without external desktop software
- Explicit coming-soon status with waitlist—not downloadable yet
- Narrows scope to original NicoVideo site rather than entire Niconico ecosystem
- Comment-preservation mentioned in skill title; README emphasizes video save on classic player
Adoption & trust: 946 installs on skills.sh; 2 GitHub stars; 3/3 security scanners passed (skills.sh audits).
What problem does it solve?
You need a concise spec and positioning reference for a NicoVideo-focused capture extension before the SERP release exists to inspect.
Who is it for?
Extension indie hackers planning NicoVideo-specific capture UX or comparing SERP’s roadmap to their own player-integration design.
Skip if: Production download workflows today, agent automation that expects runnable commands, or projects requiring comment-dan preservation details not yet documented in the README.
When should I use this skill?
When researching the unreleased SERP NicoVideo Downloader extension or its waitlist/feature positioning.
What do I get? / Deliverables
You understand planned browser-only MP4 export scope, supported browsers, and waitlist status—without a working skill-driven implementation path in-repo.
- Waitlist-oriented product specification in SKILL.md form
- Planned capability list for in-browser MP4 export on nicovideo.jp
Recommended Skills
Journey fit
Pre-release extension skills still belong on Build’s integrations shelf as specs and positioning for upcoming browser capture work. Integrations covers nicovideo.jp player hooks and in-browser MP4 export design for a single-domain focus.
How it compares
Pre-release product skill—use for scoping and waitlist awareness, not as a substitute for an shipped downloader integration.
Common Questions / FAQ
Who is nicovideo-downloader for?
Builders researching browser extensions for Japanese streaming pages who want SERP’s announced NicoVideo downloader direction before launch.
When should I use nicovideo-downloader?
During Build integrations planning when drafting content scripts for nicovideo.jp or when deciding whether to join the waitlist versus building your own capture approach.
Is nicovideo-downloader safe to install?
The extension is not released; review the Security Audits panel on this Prism page for the skill package and only install future builds from official SERP or store listings after your own review.
SKILL.md
READMESKILL.md - Nicovideo Downloader
# NicoVideo Downloader — Coming Soon (Browser Extension) > Download videos from nicovideo.jp and save them as MP4 files directly from your browser. **This extension is currently in development and has not been released yet.** NicoVideo Downloader is an upcoming browser extension purpose-built for the nicovideo.jp domain and its classic player interface. Rather than trying to cover every corner of the broader Niconico ecosystem, this extension zeroes in on the original NicoVideo site, letting you grab videos during playback and store them locally as standard MP4 files without leaving the browser. - Detect and capture videos playing on nicovideo.jp pages - Save video content as MP4 files to your local machine - Work within the classic NicoVideo player interface - Operate entirely inside the browser with no external software required - Designed for Chrome, Edge, Brave, Opera, Firefox, and other Chromium browsers ## Status **This extension is not yet available for download.** Development is in progress and a release date has not been announced. Sign up below to get notified when it launches. :bell: **Get notified when this launches:** [Join the waitlist](https://serp.ly/nicovideo-downloader) ## Links - :hourglass_flowing_sand: Waitlist: [Coming Soon — Sign Up](https://serp.ly/nicovideo-downloader) - :bulb: Request features: [GitHub Issues](https://github.com/serpapps/nicovideo-downloader/issues) ## Preview  ## Table of Contents - [Why NicoVideo Downloader](#why-nicovideo-downloader) - [Planned Features](#planned-features) - [How It Will Work](#how-it-will-work) - [Expected Formats](#expected-formats) - [Who It's For](#who-its-for) - [Use Cases We're Building For](#use-cases-were-building-for) - [FAQ](#faq) - [License](#license) - [Notes](#notes) - [About NicoVideo](#about-nicovideo) ## Why NicoVideo Downloader NicoVideo serves its content through a streaming player that does not expose a direct download link for viewers. Videos are delivered via adaptive streaming segments, and the site's comment overlay system adds another layer of complexity for anyone trying to save a local copy. Right-clicking the player offers no save option, and browser caching does not produce a usable file. Existing tools that target Niconico broadly often struggle with the specific page structures and player variations found on the nicovideo.jp domain. NicoVideo Downloader is being engineered from the ground up to handle the classic NicoVideo player, reading the video source from the active tab and assembling a complete MP4 file that you can keep, transfer, or watch offline without depending on a network connection or a logged-in session. This extension is separate from the niconico-downloader project. While that tool addresses the wider Niconico platform and its various subdomains, NicoVideo Downloader is scoped exclusively to nicovideo.jp URLs and the classic player interface, allowing for tighter integration and more reliable detection of video sources on those pages. ## Planned Features - Video detection on nicovideo.jp pages during active playback - MP4 output for broad compatibility across devices and media players - Support for the classic NicoVideo player interface and its page layout - Resolution selection when the source offers multiple quality tiers - Filename generation based on video title and metadata from the page - Download progress indicator inside the extension popup - Queue system for saving multiple videos in sequence - Cross-browser compatibility targeting Chrome, Edge, Brave, and Firefox ## How It Will Work 1. Install the extension from your browser's extension store once it is released. 2. Navigate to any video page on nicovideo.jp. 3. Begin playback so the browser loads the video stream