Hi great people out there,
I was searching for a way to put a subscription button instead of my channel link which is already exist at the widget option. I came through this following lines which I already added right after youtube tube video player iframe (line 351)
<iframe scrolling="no" frameborder="0" id="uT" src="http://www.youtube.com/subscribe_widget?p=<strong>YourChannelName</strong>" style="overflow: hidden; height: 105px; width: 280px; border: 0;"></iframe>
I couldn't find a way to style the text or the placement of the button. Also one of the drawbacks of this solution is, if you're already subscribed and you're already signed in your account the button is still there and "Now you're subscribed" success message will appear after clicking the button but it did work anyway, hope we will see subscription box integration in the next plugin release.