I've taken the spark out on a bright day in a field and the quality is terrible. Really blurry stuff. I'm using the DJI app to transfer the RAW's to my camera roll.
I had the same problem. It seems that the lines affect the cached video and not the actual video saved to the sd card. The video you download from the sd card should be fine
I'm using the video from the DJI app, there's a button that says save original which goes into the camera roll. I'll try video from the SD card direct next time, thanks!