"Swimming" texture artefact on a drone video footage
This is due to an issue with resolving an image to a set of pixels called moire.  Basically, due to the regular pattern, some parts of a straight line end up on one line of sensors and the other end up on the other.  This results in a jaggy line and the line moves around as the image moves across the sensor, producing the effect you see.  It can occur when shooting any regular repeating pattern off angle to vertical or horizontal.

The "solution" is to apply a gaussian blur (or moire reduction filter if you have one available, but it will basically do the same thing) to normalize the lines enough that they don't flicker back and forth anymore.  It results in a loss of crispness of the image, but will also deal with making the shifting less pronounced.