Congratulations you discovered ragtime piano.

Damn how can I not have noticed this until now!  But yeah good catch

Also thank you for reminding me about HIMYM, new episode out !

In the beginning it does.
Someone get Nintendo on the phone

Right, not in that video. In other clips, they play more of the song. This is the only clip I could find.

It's not exactly the same, however it is very, very similar. Perhaps the composer for the show had a thing for Mario Bros. 2.
  

So I've been watching through the past seasons of How I Met Your Mother, and last night discovered something very interesting (to me, anyway). The crazy thing is, I can't find any reference to this on the internets... am I the first to notice this??
 
In episode 19 of season 5, the sequences in which Marshall is mugged feature the theme from the first level of Super Mario Bros. 2! It's sped up and played on a piano.  It's not exactly it in this clip, but they play more of the song in other clips. This was the only one I could find. Check out the full episode to hear it.