Wish I knew what type of helicopter that is- I guess it's a Sikorsky of some kind, but I'm not sure. Some other aircraft is visible, but it's blurred.
OK, now she's trotting along; this was the first of 3 taxi runs.
After the second, Hughes throttles way back to idle.
There's no ambient sound in this clip, and the narration doesn't say much about it, but I think Hughes was taking extra measures here to keep the area clear because he fully intended to get her off the water on the third run, although it was not planned and was prohibited.
Note the excellent visibilty from that flight deck...
And off they go again, with a flotilla of aircraft and boats in pursuit, cameras cranking away.
I think he looks pretty committed to a takeoff here, don't you?

Next: The HK1, still the biggest airplane ever flown, flies for the first and last time ever!