After some trial & error I've got flv videos running OK on my slides.
When courselab publishes files, it omits to add the media_005_flv directory to 'images'. This directory is in your working, runtime files (find them by looking at the slide from inside the courselab IDE then looking in windows explorer for the most recent files saved). This directory contains the flvplayer and associated files. But, even after copying the media_005_flv directory, I was only getting the 'preloading' message. By using an alternative flvplayer (renamed to player0.swf) I got the video playing just fine. There are a few flv players available, just put the one you like into the media_005_flv directory and rename it. These different players do use different variable names, I had to edit my runtime.xml to alter some of these (eg changing objWidth to width). Its a bit fiddly, with editing the runtime.xml after publishing, but it seems to do the job. I can supply a working link if requested.