It looks like you started recording from the main sensor. If you record from the main camera (1x) and zoom in to 10x, you're not using the 10x periscope lens. UHD60 does not switch between cameras, you can only record from each lens from the start. If you want to use 10x zoom in UHD60, press the far right icon first before you start recording. Your video is just a digital 10x zoom of the main camera.
Try your video again using the setting I stated (far right icon above the mode select) and you'll see the image quality is miles better.