Is it sad

No, most of those are pretty well known.

Is it sad that I can identify every single thing in here?

Or here?

...Or in a majority of the songs in the other Niconico medleys?

As of when i'm posting this, this is already epic, and i'm only 8 minutes into the first one. All those songs are medleys of various anime background songs, themes, and lyrical songs written for anime and games, yes? So far i've noticed one of the field themes from the Legend of Zelda, a melody from KING NIGHT, and part of the dango song from clannad.