I am watching quite often DVDs in VLC on Ubuntu while surfing. As my screen isn't very big, I don't want to waste screen space. But I can't resize the window exactly to the size of the video. Changing the aspect ratio didn't help.
Here is a screenshot to make clear what I mean:
How can I get this screen space?
I had the same problem - it might have to do with the video card acceleration. Go to Tools, Preferences and then Video.
Uncheck the box about accelerated video output, under Display.
By changing the Aspect Ratio. Press the A key when playing the video to change its aspect ratio. You can also right-click -> Video -> Aspect Ratio and then choose the appropriate aspect ratio that suits your needs.
Before: (Notice the gap on the top and bottom)
After: (Notice that the black space is now filled with the video)