i have been focusing on a plugin towards the top of my sample website:

http://theplagueround.com/dev/

however it will get hidden behind any youtube video content. i have seen a publish or two about adding parameters towards the tag, but youtube can also be using iframes now to ensure that does not apply.

To possess a Youtube video appear behind your plugin, you need to add the parameter wmode=transparent towards the finish from the URL.

So change this:

<iframe width="425" height="349" 
    src="http://www.youtube.com/embed/H1Opn4DS88k" 
    frameborder="0" allowfullscreen></iframe>

for this:

<iframe width="425" height="349" 
    src="http://www.youtube.com/embed/H1Opn4DS88k?wmode=transparent"     
    frameborder="0" allowfullscreen></iframe>

More here:

If you won't want to hardcode the HTML to your posts, you need to use a wordpress plugin such as the one supplied by @Tubal Martin. It has the benefit when Youtube update their embed code later on, you need to only have to upgrade the wordpress plugin towards the latest version.

You might want to try my wordpress plugin for Youtube (4000+ downloads to date): Youtube shortcode

No design issues happen to be reported.