I don't know how hard it would be to implement, but one other thing I would like to see is a resize constrictor based on the aspect of the video. Basically, I'd like the ability of the window to resize itself so that the video always fills the <Video> dimensions completely, with no black borders. Perhaps this could be implemented by adding a autorescale="true" attribute added to the <Video> tag.
For instance, if a user resized the window horizontally, the window would automatically adjust vertically as needed to keep the video completely filled in its container, instead of resorting to ugly black borders.
This would be most useful in compact mode applications. I find it cumbersome to manually adjust both height and width of the window so that the video is filled. It would be great if VLC did this work for me.
You can best see how this would be beneficial by using this skin (requires .9). Switch to compact mode, start a video, and resize. You can see how the black borders really hurt the layout.
It would also be great if <Video> supported action="move" so we can easily move the window around on minimal skins where there isn't a lot window space to grab onto.