Thanks for pointing that out!
This video doesn't seem to be available in the US, so you can also see it in the slow motion footage here, right on the finish line:
Oh thanks for this! I had the same question and assumed the Omega branding and Olympic rings were superimposed onto the image; I never assumed it would actually be an animated advertisement timed perfectly to match the runners' pace! I assume they had a different backdrop speed for the women's race, according to their projected pace? Or would the ad look squished for them? (or alternatively, the runners stretched?)
Now that I look at it, the logos in the men's photo finish look stretched, so maybe it's calibrated for the women's pace.
They would need to know beforehand the precise span between the first and last athletes.
I think they did a pretty good job, it's only slightly stretched for an event when there was only 0,12 seconds between the first and the last runners, which is unusual.
I don’t see why the distance between athletes has anything to do with it; they record at a fixed speed which presumably is the estimated speed of the winner crossing the line. So it’s known in advance, and the stretch factor if they get that speed exactly right is 1 anyway.
And of course when I say ‘speed’, I mean [width of strip] / [time between the capture of each strip].
I was there at the time, and I could clearly see how the advertising board works. It's a vertical line of LEDs that constantly rotates through the columns of the logo. To the naked eye it just seems to be flickering randomly.
According to Reddit thread on this, the led board behind is specifically animated with the right timing so the content shows up correctly in the line camera.
