For these shots I'd give Twixtor 80% of the credit (Twixtor thread vs. GoPro thread)... look at 1:05 - 1:07, why'd they put that real cut in the middle of the twixtor ballet?
Still... absolutely stunning footage... some of the most compelling shots I've ever seen.
The Vimeo version of this confirms the use of Twixtor... and 369K hits vs 28.5K on Youtube.
What a great combo of camera, subject and software (music, too!).