To Playback the footage from the SD card, first, log into the Kami Home or YI Home app.  Select your camera inside the thumbnail to go into the "Live" view.  Click inside the "Live" view on the top half of the screen.  A timeline will appear.  The orange stripes are the clips of the footage.  Drag the timeline to a point where the orange stripe is inside the white vertical line.  At the top, "Live" will change to "Playback" letting you know you are watching the footage from the SD card. 

If you have inserted the SD card, but there is no timeline available for playback, please make sure the card is formatted.  To verify, on the home page, click on the hexagon symbol inside your camera thumbnail to go into Settings. Scroll down to the bottom and select MicroSD card under Storage.  Click on Format Storage Card.  Select ok to format the card.