Colin, I was able to download and edit the same footage. I am using a laptop with i7-4880MQ processor. I was able to edit the 4K clip with no issues. Re-rendered the full clip (over 3 minutes) to 1080p MP4 in just over 4 minutes.
On a side note, the still you can pull from the video are simply gorgeous. Printed an 8×10 photo from a still and I was amazed at the quality.