If a user sees this instruction, it likely refers to one of these scenarios:
Do not download or install "players" or "codecs" prompted by pop-ups; modern browsers can play most videos without extra software. Use Ad-Blockers: Tools like uBlock Origin
: In Developer Options, turn on "Install Unknown Apps" for the Downloader app to sideload specific media tools [1].
Each operating system handles media installation differently. Here is the practical breakdown.
The gold standard. Install the Plex Media Server on your computer, point it to your movie folder, and it will automatically download posters, cast info, and trailers.