Poster frame flashes before playing video

I have a few videos in my presentation that all start with a black frame. So to make it easier to identify the videos in Navigator view, I set poster frames for each video to visually identify them.

The problem is when the video plays, the poster frame flashes on the screen right before playing the video. It is abrupt and does not make for a smooth presentation. Why is this happening? And is there a way to prevent this from happening?

Someone suggested putting a rectangle over the video then dissolving it when the video starts... but that just makes the screen black so the frame is black again... which defeats the purpose of making the slide identifiable by using the poster frame.

Any other suggestions.