iOS and Android clients do not yet have URLs with the "n" parameter. This is why specifying the clientName as "IOS," along with the specific YouTube key, currently yields URLs that remain unthrottled.
However, acquiring this key requires decompiling the mobile application, monitoring requests through a proxy, or relying on values discovered by others. It's not necessarily straightforward.
I do agree that the code is simpler this way.
I also find it interesting that, by default, yt-dlp calls the YouTube API three times, initially as an Android client, then as an iOS client, and finally as a Web client. Depending on the video and certain other parameters, YouTube provides different formats to different clients.
"However, acquiring this key decompiling the mobile application, monitoring requests through a proxy or relying on values discovered by others."
This is again not true. The key is in the HTML of every /watch?v= YouTube page. It's a public key; it's not hidden in any way.
Further, it's possible, up until today at least, to use the "WEB" key with clientName "ANDROID" of "IOS" and receive unthrottled URLs. The key in the shell script is in fact the WEB key. The key for IOS is different.
However, acquiring this key requires decompiling the mobile application, monitoring requests through a proxy, or relying on values discovered by others. It's not necessarily straightforward.
I do agree that the code is simpler this way.
I also find it interesting that, by default, yt-dlp calls the YouTube API three times, initially as an Android client, then as an iOS client, and finally as a Web client. Depending on the video and certain other parameters, YouTube provides different formats to different clients.