Motl starts by saying that imaginary time "is the basic insight of Albert Einstein's theory of relativity." Not true. It was a basic insight of Poincare's 1905 theory and Minkowski's 1908 theory, but Einstein had nothing to do with it. Einstein did not even accept it until after all the other experts accepted it.
Einstein is often credited with being a great genius primarily because time is the most important concept in all of science, and Einstein's abstract theorizing gave us a new understanding of time. But that is entirely false. Einstein did not say anything original about time, and everything he said on the subject had been previously said better by someone else.
Separately, Motl posts 2006 videos on PBS: Albert Einstein, How I See the World:
Albert Einstein is considered one of the greatest scientific thinkers of all time. His theories on the nature of time and space profoundly affected the human conception of the physical world and set the foundations for many of the scientific advances of the twentieth century. As a thinker on the human condition, politics, and all issues of the day, he was as well-respected as anyone in his time. ...This is pretty crazy. Einstein's politics were that of Communist fellow traveler. No decent person had any respect for such views. His early relativity papers did not get him recognized as an important thinker because everyone regarded them as a rehash of Lorentz's theory.
By 1905 Einstein had brought together much of the works of contemporary physicists with his own thoughts on a number of topics including the nature of light, the existence of molecules, and a theory concerning time, mass, and physical absolutes. The “Theory of Relativity” proposed a revolutionary conception of the physical world, suggesting that time, mass, and length were not fixed absolutes, but dependent on the motion of the observer. Two years later he presented his equation E=MC2 (Energy equals mass times the speed of light squared). With this early work Einstein unhinged the assumptions of the absolute within the physical world and set the course for the scientific investigations of the century. ...
Not immediately recognized for the important thinker he was, Einstein moved through a number of teaching jobs before being offered a research position at the University of Berlin in 1914.