What was the Velvet Scare during J. Edgar Hoover's time, and how does it relate to The Crucible?

I see that you are asking about J. Edgar Hoover's era on
this question, and so I conclude that you are thinking the Velvet Scare is something
that happened during his lifetime.

I have taught US history
for years at the high school and college level and I have never heard the term "velvet
scare" in connection with J. Edgar Hoover (or in any other context, actually).  I really
wonder if you might be talking about the Red Scare.

Hoover
was connected to the Red Scare and it is connected to The Crucible.
The Red Scare was a time in the '50s when Americans were very worried about communists
in the US.  Hoover and the FBI kept files on people suspected of being communists and
such people were often persecuted.  People often say that this was a witch hunt similar
to the one in Miller's play.