It is frequently used in commands (e.g., -f 137+140 ) to specifically download the 1080p MP4 version of a video combined with the best available audio (140).

Video only (no audio), usually running at 30fps (though sometimes 60fps), and encoded with high compatibility for playback on most devices.

Are you using this for a ? If so, I can provide the specific command to download that format, or help with a command that chooses the highest quality video + audio automatically. MartinEesmaa - Youtube Format IDs · GitHub