I followed this blog and implemented the following code in the html viewer in homepagetext editor
[url=https://nop-templates.com/blog/13/how-to-add-an-advertising-flash-banner-in-a-nopcommerce-topic]
<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" height="277" width="450"><param name="movie" value="http://localhost:49933/banner/ConcordBanner.swf" /><!--[if !IE]>--><object data="http://localhost:49933/banners/ConcordBanner.swf" height="277" type="application/x-shockwave-flash" width="450"> <!--<![endif]--> <p style="text-align:center;">Alternative content</p> <!--[if !IE]>--> </object><!--<![endif]--></object>
Change certain values and width and height should do the job worked for me. Hope it helps..
Richard