Russians themselves prefer USD & EURO over rubbles and you are asking whether you should buy some 
Excuse me...where did you get the info from? That russians preffer $ over rubbles? Nonsense sorry.Ruble is going down...
Means that people are selling rubles to buy usd or euros
Who has rubles to sell... only russians.
Was it that hard?
http://www.businessinsider.com/russians-buy-dollars-but-hard-2014-12
A bank in Russia's Khanty-Mansiysk region an area in Russia that produces approximately 51% of Russian oil has completely run out of dollars and is almost out of euros, Interfax reports.
The bank still has rubles.
"Basically, what this means is that people who work in the oil industry [in Khanty-Mansiysk] just got all of their money out of the bank in dollars," a person familiar with the matter told Business Insider.
And use google translate on this one:
http://govoritmoskva.ru/news/22291/
So you can't blame it on western propaganda