This is a video of a grass snake.
Translated from RTV Oost in the Netherlands:
In the Kuinderbos near Kuinre, last year 2,500 grass snakes were born. Staatsbosbeheer says this after counting empty eggshells.
One third of young grass snakes survives into adulthood; the rest gets eaten by other animals. The numbers of grass snakes in the Kuinderbos are among the highest in the Netherlands.