If there's no direct method, DeSmuME is an open source emulator, that means you can create a custom build with the option to make the window borderless. While I've modified the DeSmuME source code before, I'm a bit unfamiliar with the Windows API...
Over the week, I tried experimenting finding a way to get full-motion video on the DS. After a few days, I managed to find a method that DID NOT require using a codec, and managed to display a few seconds of three of Juice Wrld's music videos for...