For example, see the first few scores at https://en.wikipedia.org/wiki/Cadence#Authentic_cadence. In the examples on the left, the bottom line of the staff is covered by the media player widget. In the example on the right ("A perfect authentic cadence in Beethoven's Piano Sonata No. 8"), the final note on the lower ledger line is mostly cut off.
For a very short time after page load, I see a different player (which looks like my browser's built-in <audio> widget), which doesn't overlap with the image. But then the TimedMediaHandler player renders and cuts it off.
Reproduced on recent builds of Chrome and Firefox.