This is a somewhat rare assortment of files from the Big Children's Choir ( Большой детский хор ). They are most known for their rendition of the song Прекрасное далёко (Wondrous Future), a song the children sing about a future that they hope will not be cruel to them and has since become a sort of eulogy for the USSR's collapse in Russia. 
This playlist includes my favorite songs from the Big Children's Choir, but you can download all (250+) of the files in the link provided on the TankieTube playlist or my comment on Wondrous Future.
I have transliterated all the Russian text to be more readable to English viewers, but the original files are unedited and contain their Russian names for easier searching.