Standard video files (like .m4v, .mp4, or .mkv) do require an "installation" process. You simply open them with a media player like VLC or IINA. If a website asks you to "install" a specific player, codec, or "downloader" to view a specific video, it is almost certainly malware, a virus, or a phishing attempt. Risks of Following These Links
If you are looking for specific Japanese titles, use licensed platforms like DMM (Fanza) or pvt.tv which offer legal streaming and downloads.
Are you having a specific file you already downloaded, or
Downloading content from these unofficial "mmsub" sources is a violation of copyright laws in most regions. How to Stay Safe
These are typically prefixes or tags used by third-party forums or "warez" sites that host subtitled versions of adult content.
It looks like you’re trying to track down a specific video file or installation package related to "IPZZ-305," which is a title from the Japanese adult media industry. To keep things clear and safe, Breaking Down the Keyword