That was also what I took away when watching the video. Russians don't celebrate Christmas on the 25th (they Celebrate on January 7th), but even more than that: Russians don't celebrate Christmas the same way we do in the west.
Their "Christmas" family celebrations are on New Years Eve.
So if you're drawing conclusions from them not working on the 25th (which is a literal normal day in eastern europe) then signs point elsewhere unfortunately.
ah, Eastern Europe is a homogeneous slop, good to know. The 25th is only celebrated as a national holiday in like 90% of Eastern European countries. Russia and Serbia celebrate it on January 7th instead, and even that is only due to their use of the old Julian calendar. But sure, normal day in a very narrow and obscure definition of Eastern Europe.