The default file system on a retail 32GB microSD card (FAT32) actually has a file limit of 4GB . This means most of your videos may exceed that limit due to their higher resolution.
To ensure all your videos get backed up, your Qubii app will detect the file system of your memory card and update it to enable a larger file size (exFAT). (meaning that the microSD card does need to be reformatted.
Before doing this, please save all important data prior to reformatting your SD card and inserting it in your Qubii.