Hola Ryo,
Entoces podría dejarlo así el código?
Código PHP:
<?php
//Lista de enlaces
$enlace[1]="<object width=\"340\" height=\"285\"><param name=\"movie\" value=\"http://www.youtube.com/v/60KBUdgRCRw&hl=es_ES&fs=1&color1=0xe1600f&color2=0xfebd01&border=1\"></param><param name=\"allowFullScreen\" value=\"true\"></param><param name=\"allowscriptaccess\" value=\"always\"></param><embed src=\"http://www.youtube.com/v/60KBUdgRCRw&hl=es_ES&fs=1&color1=0xe1600f&color2=0xfebd01&border=1\" type=\"application/x-shockwave-flash\" allowscriptaccess=\"always\" allowfullscreen=\"true\" width=\"340\" height=\"285\"></embed></object>";
$enlace[2]="<object width=\"340\" height=\"285\"><param name=\"movie\" value=\"http://www.youtube.com/v/gGDS_Q15xsg&hl=es_ES&fs=1&color1=0xe1600f&color2=0xfebd01&border=1\"></param><param name=\"allowFullScreen\" value=\"true\"></param><param name=\"allowscriptaccess\" value=\"always\"></param><embed src=\"http://www.youtube.com/v/gGDS_Q15xsg&hl=es_ES&fs=1&color1=0xe1600f&color2=0xfebd01&border=1\" type=\"application/x-shockwave-flash\" allowscriptaccess=\"always\" allowfullscreen=\"true\" width=\"340\" height=\"285\"></embed></object>";
$enlace[3]="<object width=\"340\" height=\"285\"><param name=\"movie\" value=\"http://www.youtube.com/v/gGDS_Q15xsg&hl=es_ES&fs=1&color1=0xe1600f&color2=0xfebd01&border=1\"></param><param name=\"allowFullScreen\" value=\"true\"></param><param name=\"allowscriptaccess\" value=\"always\"></param><embed src=\"http://www.youtube.com/v/gGDS_Q15xsg&hl=es_ES&fs=1&color1=0xe1600f&color2=0xfebd01&border=1\" type=\"application/x-shockwave-flash\" allowscriptaccess=\"always\" allowfullscreen=\"true\" width=\"340\" height=\"285\"></embed></object>";
$enlace[4]="<object width=\"340\" height=\"285\"><param name=\"movie\" value=\"http://www.youtube.com/v/ELvU4inKfQI&hl=es_ES&fs=1&color1=0xe1600f&color2=0xfebd01&border=1\"></param><param name=\"allowFullScreen\" value=\"true\"></param><param name=\"allowscriptaccess\" value=\"always\"></param><embed src=\"http://www.youtube.com/v/ELvU4inKfQI&hl=es_ES&fs=1&color1=0xe1600f&color2=0xfebd01&border=1\" type=\"application/x-shockwave-flash\" allowscriptaccess=\"always\" allowfullscreen=\"true\" width=\"340\" height=\"285\"></embed></object>";
//Calculo el numero total de enlaces
$total_enlaces = count($enlace);
//Genero numero aleatorio sin superar a enlaces
$aleatorio=rand(1,$total_enlaces);
//Escribo el vinculo
echo "<div align='center'>$enlace[$aleatorio]</div>";
?>
Lo acabo de probar y no funciona, parece que esté todo bien, no?