The Blubrry PowerPress short code supports 3 optional attributes for customizing the player behavior.

url – Specify a URL to a media file if you do not want to use the associated podcast episode
channel (previously feed) – Specify the podcast channel slug name to display only the player for the podcast specified. (only applies to custom podcast channels)
image – Specify a URL to a cover image to display in place of the player (experimental, does not work for all media)
width – set the video player width (overrides default width)
height – set the video player height (overrides default height)