Here is a link to a recent article by Ravi Nagarajan on the subject of inferring Buffett's estimate of IV from Buffett's statements and from his stock repurchases.

rationalwalk.com - Warren buffett on berkshires valuation

Ravi starts by quoting Buffett's bullish comments about Berkshire in his 2014 annual letter, when the P/B was 1.51, and then goes on to look at stock repurchases since the Feb 2015 letter. Based on a table of repurchases, Ravi states, "From this table, we can see that Mr. Buffett has been price-sensitive in his repurchase activity, but has shown flexibility as well. He has been willing to pay as much as 1.6x trailing book value, but seems far more enthusiastic when he can purchase shares for 1.4x trailing book value or less."

After the price decline since Ravi's March article, when BRK.A was selling for 1.72x "trailing" BV, Berkshire stock is currently selling for 1.57x trailing BV. If BRK.A declines another 5% (It's dropped 10% since the annual meeting from a P/B of 1.78 to 1.57x BV.), I think that Buffett will be repurchasing stock again, if he's not already.