How to make a animated login screen help

I can do everything to make my own login screen however I would like to be able to use videos as well. My problem is that when i embed the videos they do not seem to work with the league client. The file itself seems to have a working copy of a video however I can't seem to be able to get the video to work in the client. I am using flash to create my swf files. When I embed am i doing something wrong or is there another problem help pls