Getting YouTube embed videos to target an iframe on another url on my site

My homepage displays thumbnails of youtube game videos, e.g

[game1_vid1] [game1_vid2] [game2_vid1]

They currently open and play in a modal window when clicked on.

However, each game has its own page, e.g mysite.com/game1/

On that page (/game1) there is a iframe (iframe_main), and below that you will also find the thumbs for that game. So when someone clicks [game1_vid2], that vid will play in iframe_main, which is on the same game page.

However, I want users to be able to click on the thumbs on the homepage, and for the video to open in iframe_main on the relevant games page.

E.g so when someone clicks on [game1_vid2] on the homepage, the video will target the mysite.com/game1/ url, and also target iframe_main on the url.

What is the best way to achieve this?

Here is the code of the iframe_main –

<div class="iframe-container2" style="margin-bottom:0px;"><iframe width="560" height="315" src="https://www.youtube.com/embed/'.$video->YouTubeID.'?controls=1&amp;showinfo=0&amp;rel=0" frameborder="0" allowfullscreen="" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="iframe_main">

and the thumbs –

<a onclick="scrollWin()" href="/modal2/video/'.urlencode($video->YouTubeID).'"  target="iframe_main" >

The above works great, but the thumbs are on the same url, so they just target the iframe on the same page. However now I want to make the thumbs on the homepage target iframe_main, when clicked on.

I hope that all makes sense. Thanks for any help.
Chris