HTML5 3D Unavailable for YouTube iframe in IE 11

Have a message showing up in the middle of an imbedded YouTube video only on Internet Explorer (I have IE 11 installed):

HTML5 3D Unavailable
This video is not available for viewing with HTML5. You may try another 3D viewing mode.
[Change 3D viewing mode]   [Close]

It's a very simple iframe referencing a Youtube video and it comes up completely clean on Chrome and Firefox.  It wasn't there a few days ago, but now it is.  If you click on the "Close" button, it starts the video, leaves the box there and you can either choose to "Change 3D viewing mode" or "Close" which will just close the box and let the video keep on playing.

So it's more of a nuisance than anything, but I just really would like to get rid of it.