Half-Life 2: 20th Anniversary Documentary [video]

Made it through the first two video chapters and will certainly finish later on.

For a lot of similar material in coffeetable book format, there is a concept art book; searching around suggests that it is "Half-Life 2: Raising the Bar". My beloved copy is buried somewhere deep in storage, but it is a prized possession.

E: Turns out this book has gotten pretty rare, and a re-print with added content was announced as part of all of these updates.

There is another submission here[0] with a lot more traction and discussion that provides better context. There was a content update, complete with a promotional webpage and such .. which also answers that, yes, Secret Tape did this documentary as well.

[0]: https://news.ycombinator.com/item?id=42151865