I can't see any Videos/Photos on my KB X300 app

There are two sets of Video/Photo galleries on your KB X300 app. 

1. Video/Photo gallery before you connect to the camera (Next to the Connect button)

This is the local phone gallery. Any Video/Photo that you download from your X300 camera to the phone will appear under this gallery. 

2. Video Photo gallery after the camera is connected (Next to the Record button)

This is the gallery of the camera. Any Video/Photo on the SD card will appear under this gallery.