Interestingly the buffer looks to be well over 380 Mb/s and almost 3Gb large. So basically, the camera could run small sequence with lower compression in 4K or even in 8K for 3 to 6 second on the buffer, and then move that to the card when done a little bit ala phantom.
How can you record 8k video with a 18 MP sensor ?
Good point! For 8K you need at least 39MP considering the 3:2 ratio...
More desirable would be a 240fps burst mode at full-HD like the fs700 has it!