The animations display a visual defect due to interference between model surfaces. Most graphics software can generate visual defects. Actual gears cannot interfere; two solid objects can't occupy the same volume at the same time.
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Actual contact patch analysis requires a stress analysis to account for deformation due to applied loads. There is no indication loads are applied in creating these animations.
A useful analysis shows the normal and tangential stresses due to contact so that estimates of required material strength for fatigue resistance would be known. If there is a liquid lubricant involved, then a fluid dynamics analysis is also required to determine film thickness and shear rate in order to determine if the fluid is appropriate to handle the loads and to account for heat transfer as determined by the rate of fluid shear.