Thank you all for your responses. I think she
was bored of the words because when I played the new dvd she was watching attentively but when i put the old dvd back she found something else to look at

.
I tried to test her and it seems like she new the first couple of words because she would grab the right card but then she started to get some wrong and then I tested the old words and she got those wrong...I'm starting to think that it was a coincidence that she grab the right card in the beginning...She's 6 months now and I'm probably just too analytical.