How do I record this TV show?

I really love Americas got Talent but its not on iTunes or anything
else like that. They have them up on their website(nbc.com) and I
tried to record them from there using screenflow but when I checked my
recording it was terrible quality, but when I record short videos they
are crystal clear so the quality diminishes over length. I am
currently trying to record them via VHS(yeah... I know...) off of On
Demand but episode 1 is already gone off of it.

How else do I record?