Hi,
This is not my strong suit but I am playing around with .swf files in lessons at the moment. I am could be a little confused because you are presenting a "lesson" in a swf file and want to insert it into a" lesson" activity page in Moodle. Too many "lessons"
First did you read
MoodleDocs on
Flash? If you have not done so, I recommend reading the whole page, paying close attention to the section on inserting flash into a lesson page.
Next, In your site, are the multimedia
Filters turned on? I think the default install is to hide (not on) them.
I am going to assume that when you tell your favorite browser to open the swf file directly, it works. What happens when you put the swf link into a Moodle HTML resource page, can you get it to play? If not, probably the filter is not on.
I am going to assume that when you go to the Moodle Lesson Activity page which contains the link to the swf file, nothing happens. HTML resource page is more like an HTML web page than a Moodle Lesson page. There is a "helpful" feature in a lesson page that will erase any html header information when you use the HTML source toggle to edit it.
Hope this helps. Chris