The Media Player UI is closed source. Having a good solid UI concept with plenty of supportive votes does help influencing the product management plans, specially if it's true that the amount of work is small.

In a worst case scenario your UI concepts could be useful for a community OSS media player with the Media Application Framework (OSS) running underneath plenty of work is already saved.

Brainstorm is the place to submit UI concepts as solutions. You can attach images there as well. Nobody will stop you from publishing images and files in wiki or elsewhere and link from solutions but it's better to have everything self-contained.