Different media file formats encode things like time and frame rates differently… or not at all.
WebM doesn’t list a frame rate; each frame is simply given a position in time. Meanwhile the older Ogg Theora codec defines a consistent, pre-defined frame rate for a stream, but allows frames to be declared as duplicates of the previous frame as an optimization.
At the intersection of these two, some files auto-converted from WebM to Ogg on Wikimedia’s servers end up claiming to encode a “1000 fps” video stream, where nearly all the frames are dupes and there’s actually ~25-30 or at most 60 actual frames per second.
I had to put a hack into my ogv.js player to handle these, because actually trying to draw 1000 frames per second was kind of slow. ;)