It does seem that most firmware modification comes from enthusiasts in Russia. There are several forums there on dashcams, but some of them can be less-than-nice to people who don't speak the language or use Google translate. Which is why I use them only in "read-only mode" and generally only go there when I need a specific answer that I can't find here on DCT.
С 11.02.2015 доступна новая кастомная прошивка DR650_cust_1.5. (оптимизирована ночная съемка, задействован ISP, увеличенный битрейт, прошивается с карты памяти и т.д. и т.п.). Скачать: ...