The only problem with this is that they appear to have repeated the pulse multiple times to generate the video for multiple scan lines. Their camera takes pictures of a line. So to make an image, they had to use that slow-moving mirror to gather multiple lines like a raster-scan, sending out a duplicate pulse for each scan line. That won't work if you can't generate multiple equal events, such as trying to record the effects of an explosion for a film. So they need to find a way to put these cameras into a 2D (or 3D, if it's Hollywood) array instead of a line.
Also, it isn't taking pictures of photons moving through space. It's taking pictures of photons getting reflected towards the cameras from surfaces. That makes me wonder what would happen as the photographed area got deeper; the photons bouncing off the farther-away surfaces would take longer to reach the camera, and so would appear to trail the photons bouncing off surfaces closer to the camera.