WebM VP8 files obtained from youtube-dl are misdetected as having a 1000 fps framerate

I thought I had reported this years ago but somehow can't find this, and the issue is still present with GStreamer 1.16.0... but basically, grab the sample webm file here: http://pitivi.ecchi.ca/user-contributed-samples/End%20Game%20-%20Hijacking%20Epicness.webm

And look at it in Nautilus, Pitivi, Totem, etc. and notice that it is reported as being 1000 fps. However, avidemux has no trouble seeing it as being 30 fps.

This causes some pretty wonky issues with video editing, for example it creates huge proxy files.