The bit that got a lot of attention is his admission that Microsoft should have dominated in mobile (in lieu of Android). The core competencies were all there and the company was in investing in mobile at the time.
The technology discussions in general are interesting, but I also really enjoyed hearing about his efforts to address climate change. He spends a good chunk of time talking about that. Strongly recommend. (Related link: Breakthrough Energy.)
On a somewhat unrelated note, this is also the first time I’ve seen every question and answer neatly transcribed below a video. This makes it very easy to find the parts that may be of interest. All video discussions should have this.