AS2:CS3-help! -which one to use, swf or flv when importing video into swf dynamically

I am making a training video list on a web page. When a training video is clicked, the training video is played by an swf file on a new tab, and at the end of the video, the swf displays a web form to gather some data to be saved in MySQL db. The name of the training video is passed to the swf file as parameter to play the training video dynamically.

I have a question.
When loading the training video dynamically in the swf, should I load the training video in the flv format file or swf format? The training video can be produced in swf and flv format.

I noticed lots of web sites say that flv should be used. But I think training video in the swf format file size is smaller than the flv size.

What is the advantage and disadvantage of loading the training video in flv format and swf format whith all other fators being equal?

Thank you very much.