主题：【商量】一八一二年序曲与马赛曲 -- 燕人

It's a battle preparation theme of the russian army. Look at this, The 1812 Overture of Peter Tchaikovsky especially the slide "3. Russian army prepares".

I thinks it precisely refers to the theme beginning at 4:10 of your video part 1, about which you quoted

But I acknowledge that I also took this as a variation of french anthem for years. How comes they are so similar !? I guess all European army music are alike in some way. For example, the "Light Cavalry March" by Suppe.

(sorry but i can't type Chinese in my office)