Improved page speed, but with major flaw

Improved my page speed and yslow scores a lot, but every time an iframe video is lazy loaded on a page, that page is added again when I go to the browser ‘back’ button. For example, if I have 5 videos on the page and scroll down the page to load them, I have to hit the back button 6 times to get back to the previous page.

So I used the lazy load xt plugin instead and it worked beautifully.