The ballast in one of our oldest florescent lights finally died, so I thought it would be a good opportunity to replace it. 

The wiring was a bit of a jumble (I should have taken a photograph).

We have a main light, with 2 switches (upstairs and downstairs), 
then next to that, a second smaller light with a separate switch to operate that independently, which looks like it is wired to the main first light. But I'm not sure how to attach it.

I understand the 3 red wires all go together, and the three black? 
But where do the 3rd set of black and red go? :(   ...I'm guessing they might be for the second light/switch?

The picture below is of the wires which were attached to the main light, and below that is the connections to the new florescent light.




Question: Channel Entries & Relationships
Answer: Try this:

{exp:channel:entries channel="videos" limit="1"}

    &lt;h1&gt;{title}&lt;/h1&gt;

    {exp:channel_videos:videos entry_id="{entry_id}" prefix="cv" limit="1"}
    &lt;section&gt;
        &lt;div class="video-container"&gt;
            {cv:embed_code}
        &lt;/div&gt;
    &lt;/section&gt;
    {/exp:channel_videos:videos}

    &lt;ul id="carousel" class="elastislide-list"&gt;
    {parents channel="video_courses" field="related_videos"}
        {parents:related_videos entry_id="not {entry_id}"}  
            {exp:channel_videos:videos prefix="cv" entry_id="{parents:related_videos:entry_id}"}
            &lt;li&gt;
            &lt;a href="{cv:title_permalink='videos/view'}" class="image"&gt;
                &lt;img src="{cv:img_url_hd}" alt="" /&gt;
                &lt;h2&gt;&lt;span&gt;{cv:title}&lt;/span&gt;&lt;/h2&gt;
            &lt;/a&gt;
            &lt;/li&gt;
            {/exp:channel_videos:videos}
        {/parents:related_videos}
    {/parents}
    &lt;/ul&gt;

{/exp:channel:entries}


You may have to experiment with prefixes inside of the Channel Videos loop, not sure if you might need parents:related_videos prefixes inside of it - but this should get you most of the way.