Here's the video:
2013 G37 IPL 6MT stock everything. When the engine (and transmission) is cold, I sometimes get this grinding noise when pushing in the clutch. In the video, I push in the clutch for a few seconds and you hear the grinding, and then I release the clutch pedal and the grinding stops. I do it several times in the video so you can hear the difference. It doesn't matter if I'm in gear or not, and the grinding goes away after a few minutes when the engine/transmission have warmed up.

Any idea what this could be? I'm thinking my throwout bearing is going bad, but I'm not sure.

 

TOB is my first thought as well