Copia y pega el siguiente código en el código fuente de tu blog
para la correcta inserción de la pieza publicitaria:

<object classid="clsid:d27cdb6e-ae6d-11cf-96b8-444553540000" codebase="http://fpdownload.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=7,0,0,0" width="300" height="250" id="300x250" align="middle">
<param name="allowScriptAccess" value="sameDomain" />
<param name="movie" value="http://www.escrivadvd.com/banners/300x250.swf" />
<param name="quality" value="high" />
<param name="bgcolor" value="#ffffff" />
<embed src="http://www.escrivadvd.com/banners/300x250.swf" quality="high" bgcolor="#ffffff" width="300" height="250" name="300x250" align="middle" allowScriptAccess="sameDomain" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" />
</object>