Well it is nothing.
We assume that we're pushing the sine into the limiter, right? Cause that's what that guy does in a useless test of his. Let's also assume that said sine peaks at 0dBFS, for simplicity.
So for each dB we push it in, the limiter either dynamically pulls the sine down by the same 1 dB and thus does nothing because the sine stays as it is, or actually pushes it in and thus acts as a waveshaper in this specific instance, which, as I said, is far removed from any practicality.
So what's wrong?

Audio Damage Rough Rider aka The Most Compressor Of All Time?

 

I love Focusrite/Sonible FAST Limiter. If you squash the signal (I don't suggest you to do so btw) it still keeps undistorted. I also love the extra option (bass enhancing, resonance fixing, inflator-like saturation, transient shaping, autogain). Only problem it's CPU, but it's meant for mixbus/mastering

 

I find this phrase way too misleading. The results of clean limiting, or compressing, or levelling with fader sound too different to call them nothing.

Er, you missed my in the quote? I know it, but have no use for it.

 

Reminding you, we're still talking about a pure sustained sine peaking at 0 and being further pushed into the limiter.