If your videos does not play, please ensure that you are using the updated version of the application. If you have re-installed the application recently but the issue persists, please try the following steps to reset the cache:
Go to Android Settings
Go to Apps in the settings menu
Search for the ACE Online application
Click clear cache and storage data (This will remove your downloaded videos)
Quit the application and restart your phone
If this doesn’t fix your problem. Please contact the support team by submitting a ticket here