I think a close friend of hers died and the song she auditioned with was for her, hence the tears.
And Seacrest--even on a good night he can be annoying. Tonight he was insufferable. He was trying to prod Didi to tears right up until the final moments. What more do they want from her?
Seacrest has a neanderthal forehead and when he wears his hair like last night, it really shows.