embed html5 in iframe error message when viewed on iphone

I have output content from cp7 as html5 and uploaded to my server.

It played fine on my iphone 5s.

Then I tried loading it into an iframe and playing through my iphone.

It also works, but first I get a message that says it's unsupported (see image).

If I click the ok, it goes away and the content plays anyway.

Anyone know why I would get this  message and if it's valid?