Videos with sound but no images on Pavlovia

Hello everyone,

I put my experiment on - It’s a simple task: watch videos and the subject have to tell if the hand move or not. When I’m running it I have the sound of my videos but not the images, a grey screen stay all long.

I tried to modify the monitor, change brower and other stuff but nothing worked.
I put it in public if someone wants to have a look: Gautier Hamoline / handtwitch · GitLab

It’s in french, just press the left or right key to pass to other videos.

I hope someone can help me!