Weird.
Do you know (a) how this was added to the post exactly and (b) if you have any video/media WP plugins active that might be operating on the display of the content?

Yellow Swordfish said
Weird.
Do you know (a) how this was added to the post exactly and (b) if you have any video/media WP plugins active that might be operating on the display of the content?

I don’t have any other plug ins for media.  I believe the user just posted the URL into the post and somehow, it embedded the player from the URL.  

FYI, I just deactivated Jetpack and that fixed it.  But I wonder what the conflict was.

Ah Jetpack! Causes a lot of problems actually – for many plugins. In this instance I do not actually know but Jetpack has a lot of little components, many, many of which are turned on without you knowing it. I think on many of them there is a ‘learn more’ link (or something lije that) in the main Jetpack admin page – and it is only after you click on that that you get the option to deactivate bits that you did not know were turned on in the first place! If you manage to trace just which bit was causing this then it would be useful information for us all to have.

you probably could have just disabled the embed module of jetpack… not sure what it does that wp does not…