Although custom ratios are available, an option to add shortcut keys to them (eg: Shift + 4) would be useful.
This is more useful because the video doesn't maintain my 5:4 ratio I use to watch 4:3 videos on my 1280x1024 monitor. (It stretches a little, but tolerable since I like a full screen, my other two monitors are 1920x1080)
When the play-list follows through to the next video (episode), the video is reset to 4:3 even though 5:4 is still selected. (Pan+scan and aspect are default to 'as previous') Keep aspect ratio is checked.
Pro v. 2.52 Build 1030
Windows 7 x64