Looking carefully at the diagram, notice both cross team and intra-team (vertical) participation in the "communities" (horizontal). Mike is Scrum-centric, so his diagram has a Scum master community. If I'd done the drawing, I would've been less prochial since there are many competing methodologies, other than Scrum, that provide quite good agile experiences.
And, by the way, this is not an agile idea per se. I've been doing things like this in the defense and aerospace business for years (old wine, new bottle?). However, Mike's presentation is very effective. (Remember: communications = message + messenger + presentation)
And, of course, the diagram is only a hint at what you can do. It's probably best to extend this to a program or portfolio. The PMO often instigates and sponsors such collaboration.
Many groups call such a matrix "birds of a feather". I have attended many "birds of a feather" collaborations at conferences and such. But Mike is saying: make it a regular and sustained practice, not just an occasional get together.