Here is a setup of the Related plugin in which the overlay has been customized. The heading text is edited, and the thumbnails are made really wide:
Instead of navigating to the play page, it is also possible to play the related video directly in the player. That's nice in case you want people to swiftly move from one video to the next. Simply set the onclick variable to play.
Here's the contents of the RSS feed that contains the related videos:
<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/">
<channel>
<item>
<title>One Million Hugs</title>
<link>http://www.youtube.com/watch?v=smO1onPkA3Q</link>
<media:thumbnail url="http://i.ytimg.com/vi/smO1onPkA3Q/0.jpg"/>
</item>
<item>
<title>The Date</title>
<link>http://www.youtube.com/watch?v=57zo8O5pDXc</link>
<media:thumbnail url="http://i.ytimg.com/vi/57zo8O5pDXc/0.jpg"/>
</item>
<item>
<title>The Entrance</title>
<link>http://www.youtube.com/watch?v=i4m5Wkywew0</link>
<media:thumbnail url="http://i.ytimg.com/vi/i4m5Wkywew0/0.jpg"/>
</item>
<item>
<title>No Hype</title>
<link>http://www.youtube.com/watch?v=yIMTTDJv3SU</link>
<media:thumbnail url="http://i.ytimg.com/vi/yIMTTDJv3SU/0.jpg"/>
</item>
<item>
<title>April 1st</title>
<link>http://www.youtube.com/watch?v=_Pnphme2bKc</link>
<media:thumbnail url="http://i.ytimg.com/vi/_Pnphme2bKc/0.jpg"/>
</item>
<item>
<title>Brief Encounter</title>
<link>http://www.youtube.com/watch?v=P_pkeB7PbbQ</link>
<media:thumbnail url="http://i.ytimg.com/vi/P_pkeB7PbbQ/0.jpg"/>
</item>
</channel>
</rss>
Note that loading of the related videos RSS feed is subject to crossdomain security restrictions. If your feed is on another domain than your player, you will have to use a proxy, crossdomain.xml or CORS setup.