iframe does not work in redactor enabled textarea

https://dedicated1911.inmotionhosting.com/~barronfi/blog/post.php?s=2014-06-22-building-trust

In the description of the blog post linked above, I have copy-pasted the embed code for a youtube video. The iframe element that should show the video is showing our server's 404 page, saying the server cannot find, dedicated1911.inmotionhosting.com/%22//www.youtube.com/embed/iol0B-clFFM/%22.

Inspecting the iframe element reveals that the quotes around the iframe's attributes are apparently being escaped AND replaced with html entities. The following code is copied directly from chrome's web inspector

<iframe width="\&quot;420\&quot;" height="\&quot;315\&quot;" src="\&quot;//www.youtube.com/embed/iol0B-clFFM\&quot;" frameborder="\&quot;0\&quot;" allowfullscreen="\&quot;\&quot;">
</iframe>

The iframe embed code renders correctly when it is added to the postDescHTML textarea in the backend. I have tried copying the embed code straight into the textarea, into redactor's "code view" and into the textarea that pops up when the "embed video" button is clicked on the redactor toolbar, this did not seem to make a difference.

Here's the post.html template that is displayed on that page, html="true" is set on the postDescHTML template tag.

<div class="hentry">
    <h1>
        <a href="<perch:blog id="postURL" type="hidden" />" rel="bookmark" class="entry-title">
            <perch:blog id="postTitle" type="text" label="Title" required="true" size="xl autowidth" order="1" />
        </a>
    </h1>
    <p class="entry-published date">
        <perch:blog id="postDateTime" type="date" label="Date" time="true" format="F Y" divider-before="Meta information" /> 
        <perch:if exists="authorGivenName">
            by <perch:blog id="authorGivenName" type="hidden" /> <perch:blog id="authorFamilyName" type="hidden" />
        </perch:if>
    </p>
    <perch:if exists="image">
        <div>
            <img src="<perch:blog id="image" type="image" width="827" height="250" crop="true" label="Image" order="4" />" alt="<perch:blog id="postTitle" />" />
        </div>
    </perch:if>
    <div class="description entry-content">
        <perch:if exists="newsl_file"><a href="<perch:blog order="5" id="newsl_file" type="file" label="Newsletter File" />">Download the full Newsletter</a></perch:if>

        <perch:blog id="postDescHTML" type="textarea" label="Post" order="2" editor="redactor" html="true" size="xxl autowidth" required="true" />
    </div>
</div>

<perch:blog id="excerpt" type="textarea" label="Excerpt" textile="true" order="3" suppress="true" size="s" />
<perch:blog id="image" type="image" width="250" height="150" crop="true" suppress="true" />