Mads Torgersen shows the C# Language is designed in the open.
He shows how issues in the csharplang repository become proposals and shows a few language proposals. The proposals then go to language design meetings, and all the notes for those meetings are included in the repository as well. This open process allows for the community to proposed ideas and interact with the team all the way through release as an official language feature.
Here's the repo for this episode: https://github.com/dotnet/csharplang