I have been using a 32GB SD drive and working fine. Sunday I did some flying and recording and when I pressed record video I got the message about the device using cache to store video. There's nothing on my disk. What am I doing wrong?
The cached video is low-res (and sometimes glitchy) preview saved to your phone or tablet and filling up space there.
It's not something you'd really need to save.
You can turn off video caching and clear the cache space in the app settings here: