Hi, I am trying to upload a video, but there is no thumbnail when I try to upload it. Does this website automatically generate one, or do I have to find some way to add one?

Flash just gets a big image that says "Flash." Webm seems to grab a screencap of about a second in.

Furrin_Gok said:
Webm seems to grab a screencap of about a second in.

WebM uses ffmpeg thumbnail filter and I assume it's using default value, meaning it takes first 100 frames, compares them trying to find most representative frame and use that.
https://ffmpeg.org/ffmpeg-filters.html#thumbnail

This reduces the changes of black or odd frame showing up, but if e.g. 60 FPS video has first three seconds black, thumbnail will still turn solid black.

Thank you @Mairo !