The clips are based on what's happening in the original trailer, not just randomly cut to the music.

UPDATE: I've found the author of the MW3 Ponies Background pic, here's a link to his deviant art: http://sefling.deviantart.com/
And here's the background pic in 1080p http://www.deviantart.com/download/211989268/rainbow_warfare_everypony_by_sefling-d3i7nys.png

No copyright intended (Infinity Ward, Activision, Hasbro, The Hub)