It looks like Google is doing some testing, or possibly a slow rollout, of a new feature of the Play Store. The feature adds a toggle at the top of an app list in the Play Store. When toggled on, the app list will show all of the apps. . .even if you have them installed already (just like it is now). But toggled off, it will remove the apps you have installed so you only see new apps. The screenshots and video also show a newly designed app list that make the app cards more compact. This is similar to how notifications are displayed in the Android N developer preview.