It is a matter of frames per second - as the recording were done at a sample rate of 0.01, the fps was set to 100. Here is te code:
load("test1.mat");
video = VideoWriter('test1','MPEG-4');
video.FrameRate = 100;
open(video)
curve = animatedline('Color','r');
set(gca, 'XLim', [0 20],'YLim', [-200 200])
grid on
for i=1:2001
addpoints(curve,i*0.01 ,val(i));
drawnow
writeVideo(video,getframe(gcf));
end
close(video);