Planning a trip to Belarus recently, the best fare back to London was via Moscow - so I looked into whether I needed a Russian transit visa.
Both the London and Washington embassy websites stated that:
Passengers travelling to the Republic of Belarus or the Republic of Kazakhstan via the Russian Federation must obtain Russian Transit Visas
I have bolded "to", as I understood this to only mean to - rather than both to and from. This meant that I booked flights out of Belarus via Moscow to avoid the extortionate £80 fee (or £125 if you need it quickly).
You can imagine my horror at the airport in Minsk when I was told that I did in fact need a transit visa to travel via Moscow. I double and triple checked it with different Belavia staff at the airport - and I was told that it common error that European passenger make.
The result was that I had to book a different flight back home to London - there was by chance a direct flight leaving a couple of hours later. And of course my flights via Moscow were non-refundable, so I lost them.
Russia's London embassy visa agent have now changed their advice to read:
Passengers travelling to and from Belarus via Russian Federation need to obtain the transit Russian visa irrespectively of their length of stay in the airport.
But it's too late for me :(
And Russia's Washington embassy website is still showing the incorrect information.
A friend subsequently told me about the useful Star Alliance Timatic service which provides the detailed information that all airlines use in deciding whether to allow you to fly. This does indeed state that you need a Russian transit visa.
Apparently the reason you need a Russian transit visa is that flights to and from Belarus arrive into the domestic terminal in Moscow, so it's not possible to stay airside in the Transit Zone.
I guess the time and money I spend learning this lesson could have been worse - so maybe I was vaguely lucky to learn my error this way !