Notice how the contents never change. You can 
stop the video and see the file names for yourself.
In contrast, watch what happens here.  The
 contents of the box change in an obvious way.
00:00 / 00:00
Speed
1x
0.5x
0.75x
1x
1.25x
1.5x
1.75x
2x
Quality
720p
Auto
720p
360p