Bergamote,
The reason for the early stop phenomenon that you observe is that bright portions of the scene do not losslessly compress so well as darker ones. Therefore, the brighter your scene is, the less is the compression and buffer fills much faster causing the camera to stop early. When you move the camera during filming, watch for the color of the time indicator. It should be green but when the sky or a brightly lit object enters the screen, it turns yellow, orange and red. If it turns red, recording will stop any moment.
To avoid this, do the following:
1) AETTR your scene and once you are sure you have proper exposure, dial it one stop back
2) Focus precisely on the main object that you need to place the accent on
3) Activate Dual ISO and select the higher value to be two stops higher than the lower one as selected in 1), e.g. 100/400. This will compensate for the lower signal-to-noise ratio in the shadows as a result of the reduced exposure in 1)
4) Start filming. Now the scene will not contain too bright areas and compression will work just fine. You will get continuous recording. As a bonus, you will also get a brighter striped preview which will help you frame better. But watch for the icon color. If a large and very bright object enters the scene, it still may turn red and you may not have enough time to avoid camera early stop.
5) Process your files with MLVApp and enjoy stunning video quality !!!
6) And don't forget to thank the developers for this miracle!