Jason:

  video.width = video.videoWidth;
  video.height = video.videoHeight;



THIS WORKED! Y’all are heroes.
Do the width and height of the video element in the DOM matter?  I assume those values have nothing to do with the size, given that the element looked fine before, but it’s worth checking.
e.g. if I stretch the element to the full page, is that going to make TensorFlow act funny?