On the main screen of the flight app, there is a 'Play' button - bottom right next to the Task/Camera setting. You can click that any time (you don't need to be connected to the drone) and there's a simple list of videos/photos from your flights.
My App (Flight Center - here) also synchronises those videos and photos with your telemetry so you can see where you were when they were taken. You can play back the video and watch the drone fly the route at the same time. It also lets you download the videos and photos to your PC through your browser.