Having watched it more closely.  Is that really a monstrous fan??  Not actually sure. 

I think it is a fan, and it is turning. But I doubt any positive effect on the evaluation board, it just is not directed enough. I would also say it belongs to the equipment behind the fan and even blows warm air to the chiplet. Put the evaluation board 15 cm to the left and everything is OK (even if it´s only for the video!).

The video is likely recorded with a mobile phone so the micro is in the middle of the room. Therefor the fan noises come from all the hardware around. No technical interposer problem here but the video quality goes down.

What is the purpose of this video? Bad quality, twitter rush job. It is a live proof of the 400G-Transmit-specs at best. As an OFC-roundup it would be.... sad. There must come more.