Some quick tests

Let's see if this works!
First of all, embedding Flash files (SWF format) into a blog post (please be patient while loading 540 kb flash file):

You should see a small video in the above space. Or, at least, some warning, like "You do not have Adobe Flash Player Installed" or "You do not have the latest version of Adobe Flash Player".

Now, let's move on... Well, let's move to the next post, we don't want to screw up the whole system at once.
Now, if you are curious about embedding Flash SWF intro Blogspot, use this HTML Code:

<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash /swflash.cab#version=6,0,29,0" width="405" height="400">
<param name="movie" value="file_url">
<param name="quality" value="high">
<embed src="file_url" quality="high" pluginspage="http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash" type="application/x-shockwave-flash" width="405" height="400"></embed></object>

Of course, as you can see, you have to upload the SWF file into an external location that allows hotlinking and put the actual link instead of file_url. Also, don't forget to chande width and height of the video.
If you have a paid hosting account, that's just great.
If not, you can use a free hosting site. I use www.fileden.com
With a free account, you get 1 Gb of storing space, 5 Gb of bandwidth each month. Free accounts get warnings after 30 days of inactivity and are locked/deleted after 30 days of inactivity.