[tutorial] How to download Nico Nico Live stream archive

1) Download yt-dlp.exe here.

- Create a new folder and put the file here, then copy the path to this folder. This folder will be where your download is saved.

For example: "C:\yt-dlp\"

2) Install FFmpeg

- Download here.

+ Recommended build: Windows builds by BtbN (Choose ffmpeg-master-latest-win64-gpl-shared.zip)

- Watch how-to-install tutorial video:

or follow the instructions below:

+ Extract the zip file, rename the extracted folder to a simple name as "ffmpeg" and move the folder to C:\ 

+ Copy the path to the sub-folder "bin".

For example: "C:\ffmpeg\bin"

+ Search for "Edit the system environment variables" on your computer search bar and click to open: "Environment Variables" => Path => Edit => New => paste the copied path above, choose OK to finish installing.

+ Check if ffmpeg is correctly installed: Open Command Prompt (Press Win + R, type cmd, press Enter) then type this command and press Enter:

ffmpeg -version

3) Open the stream/video you want to download in FIREFOX:

- If your stream is paid/membership-locked: Log in to your Nico Nico Live account with that you purchased the stream, open the stream and skip to the paid part and leave the stream playing on its own. 

🔻Note:

+ Only works with Firefox (Chrome requires an extra step that is too time-consuming imo)

+ If you're not logged in/logged in to the wrong account, only the trial part of the stream will be downloaded.

4) Open Command Prompt and paste the command there and press Enter:

- Change to the folder: 

cd "path to new folder"

For example: cd C:\yt-dlp\

- Download a stream archive/video:

yt-dlp --cookies-from-browser firefox "stream link"

For example: yt-dlp --cookies-from-browser firefox "https://live.nicovideo.jp/watch/lv350606755"

 - Wait until the command output shows "Deleting original file "file name" (pass -k to keep)" like this:

 - Your download is saved in the same folder yt-dlp.exe is located.

Reference:

1) yt-dlp - a feature-rich command-line audio/video downloader: https://github.com/yt-dlp/yt-dlp#installation

2) FFmpeg - the leading multimedia framework, able to decode, encode, transcode, mux, demux, stream, filter and play pretty much anything that humans and machines have created: https://www.ffmpeg.org/download.html#build-windows

3) Geeky Script's "How to Install FFmpeg on windows 10 [2025 Update] Complete Guide | ffmpeg Video Conversion Tutorial": https://youtu.be/RNf8I2nxFKw?si=vxxdubXhuHHUNoQh>