I think you described it correctly, but in all honesty, what's the difference? They're able to capture, very precisely, a trillionth of a second worth of a line of reflected light. They then repeat it until they get a video. And, since a line isn't very interesting, they repeat it in a bunch of lines parallel to each other to get a rectangular video.

Sounds a lot like a CRT. Or some of the oldest video capturing techniques (scanning line by line into a photo diode, and then using that signal to vary light on the output following the same scanning pattern).

The only thing that this camera is missing from other high-speed cameras is 1000 more lines in parallel, and a faster cool-down between frames. And many high-speed cameras in the past got around the cool-down by using multiple cameras, each taking a different slice of the action, and stitching them back together afterwards, but they're still considered high-speed cameras.

This could be 100% identical if they built a million of them and took a video in one shot, but it isn't currently feasible or cost-effective. And, since their 'bullet' is non-destructive, there's no reason to not simply repeat it with a cheaper technique.

That only works for static scenes with a predictable light source. So it wouldn't work with a light source that you don't control. Also it might or might not work for e.g. medical imaging because a person can't sit perfectly still. So for those cases you do need the million camera version.

One of the big benefits of better imaging is serendipity -- being able to see things you didn't expect to see or have to plan to see.

So, you could assume that the scene is static, but that's just not true in any scene.

Look up Debevec's Light-stage work on Digital Emily. One of the unanticipated benefits of fast, high-detail face capture is that we get to see how skin really deforms. This after decades of papers on how skin is supposed to deform.

Well before reading the article I was struggling to imagine how to film light - after all either a photon hits the sensor or it doesn't. How would you photograph a photon in mid-flight? You can't, because if it is in mid-flight, it is obviously not on your sensor. So this (presumably correct) explanation is a relief for me.

It did sound like that from the description and some of the earlier footage in the video, but no, they're still capturing reflected light :)

How they able to repeat the scene each time exactly?

In a similar vein, this striking anti-gun commercial by a local radio station in London: http://www.youtube.com/watch?v=DKAnmqdfGQY

It's even possible (although of course difficult) to make a film camera that operates at 1 million frames per second. They were mainly used to analyze explosions I think.

This new camera has limitations of course, but it has a time resolution literally 1,000,000 times the one in your video.

I'm still not sure this is how it works. They are talking about 500 sensors. When those sensors can capture @ 10000 fps, you might get a 'movie' of 5 million fps. But then again they also use the bigger mirror to scaneline the scene. Maybe it's a combination of both?