(Android/VR) How to get video from local sdcard

Hello. I have been developing an application that requires the storage of some large 360º videos which exceed the 2GB OBB limit. The application isn’t for commercial download so the size isn’t an issue but want to save these videos on the headset’s SD card separate from the app package.

I have added READ_EXTERNAL_STORAGE and WRITE_EXTERNAL_STORAGE permissions to the manifest file, but I am not able to access any files even using absolute routes. Information online is sparse and the documentation doesn’t have anythong about how to go about doing this! Thankyou so much in advanced if anyone has had experience with this.