https://www.youtube.com/watch?v=OKKbkS_LOu4
2:27 : "Einstein showed that the faster one travels, the slower time goes for the traveler."

This does not follow from Einstein's 1905 postulates. The valid conclusion from the postulates is:

The faster one travels, the FASTER time goes for the traveler (he sees his clock running faster than stationary clocks):

http://www.people.fas.harvard.edu/~djmorin/chap11.pdf
Introduction to Classical Mechanics With Problems and Solutions, David Morin, Cambridge University Press, Chapter 11, p. 14: "Twin A stays on the earth, while twin B flies quickly to a distant star and back. (...) For the entire outward and return parts of the trip, B does observe A's clock running slow..."

Pentcho Valev