I can't believe I'm installing "last night's build" of anything on one of my production machines but it's done.
And it didn't seem to have any effect. I still get "The file format plugin for the specified format was not properly initialized." in Vegas Platinum 8 with Windows XP Pro SP2.
I couldn't reach the second link you quoted from the Russian site.
The .exe url works for me...
I understand that this can be a bit scary btw. Try also re-installing Vegas indeed. I could playback your "hello" file on my Vegas. :)