This assembly was made in Solidworks, but is being edited in Solid Edge. So Solid Edge is changing imported parts in the assembly. Not adding features, but changing dimensions. Multiple parts the assembly simultaneously, and matching faces from other parts. On the fly.
This would be the equivalent of setting up a couple of in-context relations in history software. And just like the other video, these edits could go either way. In history, you have to commit to changes going in a single parent/child direction. In synchronous, you don't have to worry about parent/child.
Check out this video.