In theory, you might be able to detect the video type without needing a manual 10:3 mode toggle button in the UI. When you encode a video with x264, you can set the SAR of the clip with the --sar switch. For 800x240, you would use --sar 1:2 (800 * 1 / 2 = 400, 400 / 240 = 1.667 = correct DAR for playback). If you can find the SAR flag in the video, you could potentially enable 10:3 mode silently for videos that need it. MKV also has a similar aspect ratio flag that you could use for auto detection, and I think MP4 does, too. Checking the SAR of the H.264 stream would allow you to use one detection method for all containers, though.