This happened to me on my Mi Mix 2 as well. To fix it I did this:
1. Installed Magisk
2. Installed 'Root Uninstaller' from the Play Store
3. Used the 'Root Uninstaller' app to uninstall 'Mi Video' then rebooted my phone
4. Installed the latest 'Mi Video' apk from here
Now Mi Video works perfectly again and I didn't have to wipe my phone
Edit: Magisk is rooting your phone. Android Pay etc still works fine with it but my banking app detected that I had rooted and stopped working. To fix this I installed Magisk Manager and used Magisk Hide to prevent my banking app from seeing that I had rooted. If you run in to any similar issues doing this should fix it for you too.