I can understand wanting to watch the videos you recorded on your device. When it comes to symptoms like this, the very first thing I would recommend doing is to do is the forced reboot. It is a simulated battery removal that is effective in fixing minor software-related symptoms like this.
How to Force Restart your Galaxy A10
Once your phone has successfully rebooted, try opening the gallery app and see if it still crashes or closes after it’s launched. Also, try taking a picture or video using the camera and then preview it. This will also test if the gallery is showing this symptom still. If you are still experiencing the symptom, I would recommend testing the device in safe mode to see if you are able to open the Gallery app properly. You can put your device in safe mode by following these steps.
While in safe mode test the Gallery app. If the symptom stops this will indicate there is a 3rd party app causing this to happen. If this is the case, you will need to uninstall the most recent app downloaded before the symptoms started. You will need to do this with each most recent app until the symptom stops. If the symptom persists while in safe mode, I would recommend wiping the cache partition on your device by follow the steps below.
After the reboot, find out if the Gallery app is still showing the symptoms. Let me know if this helped!