make video background transparent or white

Hi, I have embedded a video from Vimeo into the header of the site using 'Revolution Slider' and the slider is set to be responsive. The problem is that the background to the frame that holds the video is black and it shows when the browser is changed in size. I have tried to alter the colour with CSS but can't seem to get it to work. Ideally I would like the frame to be transparent but white would be better than black.

Could you take a look at this for me?

Thanks in advance.