Video button


I am trying to create a video button - so you roll over an image and it plays like a video. Tiny compression just a little larger then a thumbnail.

It works fine in flash but when i publish online - some of the buttons/video vanish, and every refresh is a bit random, so some work at times then not at others.

Has anyone got any advice why, or a better way of doing this - i have tried exporting the buttons in through a placeholder but then the videos do not work when rolled over.