"Wir fliegen - Xenoblade Chronicles X" is a high quality rip of the OST version of "Wir fliegen" from Xenoblade Chronicles X.
Joke[]
At 0:13, the male studious voice of Cross, the game's customizable main character, says "It's time." He then begins repeating various arts from the Dual Guns and Longsword weapon classes, as well as Soul Voices and the yell heard when he takes knock back from an enemy attack. The intervals between the voice lines get increasingly shorter as the video continues, until eventually multiple voice lines are repeatedly played over each other.
The rip is parodying how Overdrive, where "Wir Fliegen" plays in the game, allows players to use arts much faster than otherwise possible. The use of Dual Guns and Longsword arts is most likely referencing a meta in the game, in where large amounts of damage can be done using a build with these two weapon types.