Ho trovato pure questo, il problema però è che escono delle x rosse al posto delle thumnbail. Essendo del 2008 tipo sicuramente avranno cambiato qualcosa.

codice:
<style> ul { list-style-type: none; } </style>    
<td width="800" hight="800" valign="middle" class="headerNewsFlash">
<marquee id="newsFlash" direction="down" scrolldelay="30" scrollamount="4"><div style="width: 0px" onMouseOver="newsFlash.stop();" onMouseOut="newsFlash.start();"><nobr>
    
<?php

//Codefreek Production 
    //www.talkphp.com 
    //BETA 0.1 RSS Grabber From Youtube 
        //Copyright 08 - 09 by codefreek
            //if you like please pm me and say thank you and i will continue doing more free scripts.

    //only use when needed!
    //ini_set("user_agent","Internet Explorer");

    //Edit here for your rss link
    $location = "http://www.youtube.com/rss/user/sonicdreamdatabase/videos.rss";
    $contents = file_get_contents($location);
    $xml      = new SimpleXMLElement($contents);
    $limiter = 0;

    print "<ul>";

    foreach($xml->channel->item as $item) {
       print "[*]";
    $linkarray = explode("=",$item->link);
    print "<a href='".$item->link."' title=''>";
    print "<img src=\"http://s2.ytimg.com/vi/".$linkarray[1]."/default.jpg\" title=\"My Thumbnail!\" />";
    print "</a>";
    print "";
    $limiter++;

// here you can change the 10 to the limit
//you want!

    if ($limiter == 10) break;
  
   
    }

    print "[/list]";


    ?>

</marquee>


</nobr></div></marquee>
</td>
<center>Youtube RSS Grabber 0.1 BETA - By Codefreek</center>