You can import the FLV video onto stage and timeline using File -> Import -> Import Video option. Popup dialog will open. Select second radio button 'Embed FLV in swf and play in timeline'. Browse for the video file and click Next. Select 'Place instance on Stage' and click Next. Click Finish to import your video on stage. Click 'Ctrl+Enter' to test your video. It should auto play and loop indefinitely.
Hope this answers your question.