I'm using the 'poster' attribute on a video tag and the way it seems to work at least in webkit browsers is that it loads the poster image and then once enough of the video has loaded, it replaces that poster with an auto-generated poster from the video file itself. However, my poster images don't match the auto-generated posters which results in a weird experience of one image loading, then being replaced in a few seconds by the auto-generated image. Is there any way to prevent the auto-generated image from being used?