Explanation of how to link to a structure from a structure
I'll assume that 'watch' is a landing page in which you want to list out the various sermons from the sermons structure. In which case you can retrieve and display those in the 'watch' template using a for...in or a nav...in loop. For example:

{% set sermons = craft.entries.section('sermons').limit(null) %}
&lt;ul&gt;
    {% nav sermon in sermons %}
        &lt;li&gt;&lt;a href="{{ sermon.url }}"&gt;{{ sermon.title }}&lt;/a&gt;&lt;/li&gt;
        {% if children %}
            {% children %}
        {% endif %}
    {% end for %}
&lt;/ul&gt;


In your 'sermons' section settings you can then set the top-level uri to be:

watch/{slug}


And the nested uri to:

{parent.uri}/{slug}


In this way, you can set the uri's to match up nicely, with the index page as 'watch' and the sermon entries as 'watch/sermon-parent-slug/sermon-slug'