The video appears to originate from somebody in Norway with early access to the console, as spotted by Eurogamer (opens in new tab). It's already been taken down and rehosted several times since it first appeared. The image quality of the video is very poor, and it only lasts for 29 seconds, but it doesn't need to be fancy to show you exactly what you want.
From the new PS5 UI dashboard, it takes about 7 seconds for Spider-Man: Miles Morales to launch to the main menu. The video doesn't appear to show resuming a suspended game, that's just how fast it loads the whole thing. It takes 2 seconds more - if that - to load into the open world from the main menu, with Miles perched on top of a building and ready to start swinging.
All told, that's less than 10 seconds to get into the game, and the process will almost definitely be shorter if you're loading a suspended game instead of booting up a new one. Times will naturally vary from title to title, but with all the emphasis Sony has put on cutting down load times for PS5, this will hopefully be the new way of things overall.
Honestly, I understand why Sony wouldn't want this look at PS5 circulating early, but this is at least as good of a commercial for the next-gen console as that one with the boats.