The black bars simply fill space based on the dimensions set for video size. There may be settings for that, don't remember. It has been some months since I worked on this plugin and so it is overdue for an update. The dimensions do exist in code and they are meant to exist as UI options. If they don't they will be added.
As for the play-icon, it depends on what YouTube allows. I don't remember seeing a YouTube video or any video for that matter without an icon in the middle or a different icon. What one could do is create a video icon that overlays the featured image you upload for a video post. So essentially your displaying a post, a featured image and icon to indicate it is a video. We see this in a lot of themes.
If YouTube or other video services allow a custom icon I'll be happy to add that ability.
I like the black and white idea. Have you seen this done elsewhere? Again it depends on YouTube ability. I've noted this to be followed up when I work on the plugin and look forward to it. I like the idea myself.
I'll spend a week on it soon.