How to make an iframe valid?

Question

Google

I never bothered about posting videos in articles, I took the code from Youtube and inserted it into an iframe on the site.
Here's what I don't like about Iframe :
it is not indexed by search engines and as a rule the code is not valid.

How can iframe code be used to give it validity without using javascript, or is it better to use micro-markup from Yandex or Google?