I learned a few things when trying to follow the video. The two points used for the links -must- be separate datum point features. If they are 2 points made in the same feature, the assembly constraints will fail (drive me nuts!).
I could not figure out how to drive the 1st link as a servo motor. Although I had a logical solution, it would not run through the analysis. It stopped every time it reached the straight line.
Therefore, I added a "drive wheel" consisting of a line. I then added an additional slot constraint to the 1st link to pull the chain along. Obviously, the velocity is not constant as the drive wheel moves the chain. A few behind the scene tricks can compensate, such as a custom motor curve or even moving the motor with another motor. It can get complicated. But for basic Creo's mechanism, I am happy with this result. See if it works for you.
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...and if you don't want your links to reverse themselves, I might recommend adding a limited angle range in the Pin constraint.