The screen must be clicked for the videos to play - the error will show up as all black shapes/meshes for the video texturesFromFile
just reload and click the screen right after a few times - should be fine (same deal with playing an audio file in html - it's why the scenes always start muted)


if you've loaded the video in another tab, this will cause a cors issue. Clear the video file from your history (should be easy to find the exact one) - reload only in 3d viewer so it's tagged as cors when loaded, otherwise the cors error propagates thru all tabs (unlike images - videos are nastier here)