Did you try if this happens with H264 too? My ipad4 mini does this too even at 19 deg C. So i do not think its a temp issue..I flew today and took off HD mode, put the tablet in airplane mode, no cache recording and still got the error and my screen froze up. It only happens during video recording so I guess it narrows down to the 4K HQ mode with h.265 or my micro sd card which I never had problems with before, but I guess there's more of a load on it now. Hmmmm