And when he flatly says "the population became 80-85 percent Russian", he's referring to the time period after the 1944 genocide (which he's choosing not to mention for for some reason). Before which the Russian population was, as he knows, always a minority. Moreover, essentially all of the influx of non-indigenous groups after 1783 was as a result of settler-colonialist policies of the Russian and Soviet empires. Before which the population was 93 percent Tatar, about 7 percent other groups -- with no Russian population to speak of.
https://www.youtube.com/watch?v=Gr5PRtnqaWI