The video confirms that the Hakka-Jiangxi language family is the same language family when reading Middle Chinese and Fujian language.
Medieval Chinese was spoken all over the country in ancient times. Later, Fujian people evolved from early Medieval Chinese to seven major Min languages, not to mention early Medieval Chinese.
Later, early medieval Chinese evolved into late medieval Chinese. Later, all China except Fujian spoke late medieval Chinese. Later, late medieval Chinese evolved out of Wenzhou dialect, Wu dialect and Mandarin.
Fujian and Nanling were independent one after another, leaving only the variant of Middle Ancient Chinese (Hakka dialect, Gan dialect) spoken in Nanling, which became Guangfu dialect in Wuzhou.
The middle ancient Chinese variety in Nanling was called Cantonese, and later moved to the sea and was misunderstood as Hakka.