UniversalViewer can't read the video files

I use Omeka 2.7.1 UniversalViewer 2.5.9.

I registered “webm” and “ogv” files as items, but I can’t read the video files in Universal Viewer. The squares have been going round and round in the viewer. The image files are showing up fine.

I haven’t set up the IIIF server, is that the reason?

If you know of any of them, please help us. Thanks.