Or you can try explaining that every episode generally has all the
information you need to follow it. We're constantly adding new viewers,
and they're almost always up to speed in just 2-3 episodes, if that long.
Just jump on in, the water's fine.
The occasional repetition of some bit of background or foreshadowing can
be slightly bothersome for constant viewers, but that is necessary if
you're going to continue to add new viewers, which is important for any
series to stay on the air.