If your goal is to save data or storage by downloading the absolute smallest MP4 version, you can use the following methods:

: It is frequently sought after because it offers a balance of HD quality with relatively low file sizes compared to higher resolutions. How to Download the Lowest Quality MP4

: Lowering the resolution (e.g., from 1080p to 360p) is the fastest way to reduce size.

: MP4 files using the H.264 codec are the most compatible, while H.265 (HEVC) can offer even smaller files at the same quality level, though it may not play on all older devices.

: To target a specific small MP4 resolution, use: yt-dlp -f "best[height<=480][ext=mp4]" [URL] .

: For advanced users, tools like yt-dlp allow you to specify the "worst" quality to ensure the smallest file. Command : yt-dlp -f worst [URL]