Why do most of my mp4 files in the resource folder have triangles and an exclamation mark inside. The video component can play videos not on youtube, Right?
I redid all the videos with Handbrake with web optimized. All good now. Triangles are gone.
Those triangles are a sure sign when something is not right. I often see them if an SVG is not correctly formatted.
That indicates that Elements can’t generate a thumbnail for that file, it can happen for a variety of reasons, the most common being the resource is not in the correct format.
Elements will still export the file, and if the browser can preview it, it will still work.