I have exactly the same problem and I am glad to see someone has already mentioned this.
Here is an exmaple: I insert this into the code:
<object width="425" height="355"><param name="movie" value="http://www.youtube.com/v/rP5y7yp06n0&rel=1"></param><param name="wmode" value="transparent"></param><embed src="http://www.youtube.com/v/rP5y7yp06n0&rel=1" type="application/x-shockwave-flash" wmode="transparent" width="425" height="355"></embed></object>
I press source to go back to normal view. If I press source again, this is what I get. The source is cleared with about:blank which means the flash file will not be displayed.
<p><object width="425" height="355">
<param value="about:blank" name="movie" />
<param value="transparent" name="wmode" /><embed width="425" height="355" wmode="transparent" type="application/x-shockwave-flash" src="about:blank"></embed></object>
Here is another example. I use
<embed width="486" height="412" pluginspage="http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash" swliveconnect="true" type="application/x-shockwave-flash" seamlesstabbing="false" name="flashObj" base="http://admin.brightcove.com" flashvars="videoId=769654555&playerId=769469373&viewerSecureGatewayURL=https://services.brightcove.com/services/amfgateway& servicesURL=http://services.brightcove.com/services&cdnURL=http://admin.brightcove.com&domain=embed&autoStart=false&" bgcolor="#FFFFFF" src="about:blank"></embed>
and it remains the same, though it doesnt play back at all.
Then I did some further tests on my other portals and I discovered that the behaviour is differnt on my portal 0 than others. In portal 0, the first method of inserting an object works. FCKEditor doesnt overwrite it. But it is overwritten in all other portals.
On the other, hand the embed method gets completely cleared when I switch source in FCKEditor in portal 0.
So in summary, embed method doesn work at all anyway. The object method only works on one portal and not others.
My feeling is that this is related to security. I did all of these tests logged in as admin, so naturally there shouldnt be a problem. I am using DNN 04.05.05.
The question is how can I get insert flash activate in FCKEditor without it getting blanked.
Any help will be appriociated
Thanks