At all three cadences he looks just fine, although the constant shift in camera angles and the way the film is process makes it difficult for the viewer to get a sense of what this rhythm looks and feels like for a sustained period of time. But ridiculous? No. This runner looks quite comfortable and natural. Slightly too much bounce for my liking, but nothing ridiculous here.
I've watched elites jogging before races and it's true that the Kenyans, at very slow warmup paces, don't stress about maintaining high cadences. But three or four times a week I run on a trail used by Ole Miss XC runners, and when they pass me--especially the women--I sometimes try to sync my pace with theirs, just as an experiment. I'm always surprised by how fast they're turning over, and how it doesn't LOOK as though they're turning over quite that fast.
I'm one of the runners who paid a lot of attention on this forum ten years ago when Jack Daniels and others, if I'm not wrong, talked about the 180 cadence. They didn't just make it up; they came up with it after counting the cadence of the runners in a number of track races.
It's a pretty good general guideline. I managed to increase my cadence from the high 160s to the mid-to-high 170s, and I'm glad I did. There's a certain power that I FEEL when I've got my form right--very slight forward lean, a sense of coming over the top of my feet (whatever that means!), and a quick, easy cadence. It's real. But cadence is just one part of the equation.
I've seen many, many hobbyjoggers who could benefit from thinking about cadence, and from adjusting the relative proportions of stride length and cadence--shortening the former, speeding up the latter. I also particularly see this problem in Joe Undergraduate, who skips off into the woods every now and then, shirt off, to show the world how good he feels and how fast he is. These guys, too, would benefit from shortening the stride a bit and speeding the cadence up a bit.