Update 1: 2018/08/30 10:47am PDT
The per-device media defaults seem to be an old feature, so far as we can tell, though this is the first time Google has formally announced them. It even
Back at I/O 2017, Google showed off what it called "contextual visual responses." Put simply, they were visual feedback for Assistant-based queries on your Chromecast. Earlier this year, we spotted the first of these in the wild for weather, and next up was YouTube.Read More
More Assistant-triggered visualizations are coming to Chromecast, plus per-device casting defaults for Google Home was written by the awesome team at Android Police.