Your hi res. pics & videos are saved on the sd-card in your MA2s ... nowhere else. If you want them transferred to your mobile app you can do so within the app, but that will take time & consume a lot of battery as the drone, RC & app needs to be on during the whole transfer. Furthermore your phone isn't the best device to deal with hi res. videos ... your computer is much better suited for editing work.
Sometimes (usually?) you can find low res cache copies of your pics & videos on your mobile device ... but as they are low res they are pretty much only good for checking off compositions & such (... but this with cache files have always been rather unreliable & a hit and miss on all DJI crafts).