I use desmume because of it's built-in AVI recording feature, which is great to record my Pokemon Wi-Fi battles, and post them to Youtube, but I'd like to see some improvements on it, for example:
-Support for the magnification filters while recording (that can be found at "View>Magnification Filter", at least in builds newer than 0.9.5): for example, I have the window with the double size due to the "HQ2xS" filter, and that somewhat improves the quality of images and text. But when I record, it records at the normal screen size, without the magnification filter. When I scale the video on my video editor, it looks blurry. The only way around this is to use a screen recorder, which doesn't record with much quality, and even on my relatively powerful computer, it lags a bit, and misses quite a lot of frames.
-Allow the user to choose whether to record the top, bottom or both screens: This is pretty much self explanatory.