I think Buffett calculates BRK's intrinsic value in two ways, one a short-cut way and the other the more comprehensive way.
The short-cut way is to define the intrinsic value of BRK's investments in KO, G, etc. as merely their market price and to then come up with an "investments per share" figure for BRK. In the last 3 Letters to Shareholders, Buffett has been providing a table showing BRK's "investments per share" and Buffett asserts that this figure is the first component of BRK's intrinsic value (the other component being the intrinsic value of BRK's wholly-owned subsidiaries, determined by discounting their aggregate earnings and earnings growth rate).
The more comprehensive way that Buffett determines BRK's intrinsic value is to look at not only the earnings of BRK's wholly-owned subsidiaries (and discounting them) but also to discount the "look-through earnings" of BRK's holdings in KO, G, etc. Since Berkshire actually owns 8% of Coke's outstanding stock, Buffett believes Berkshire (and its shareholders) have a claim to 8% of Coke's earnings -- just as if BRK owned 100% of Coke, BRK (and its shareholders) would have a claim to 100% of Coke's earnings. The SEC merely has a rule that says if you own less than 20% of a company's stock, you can only claim the dividends on that 20% as your own income and not 20% of all the earnings outright. But in the case of Berkshire, even if it owns less than 20% of Coke, 8% of Coke (worth about $16 bil.) is still a huge amount of Coke stock, so Buffett has a case when he says Berkshire can properly claim 8% of Coke's earnings as its own earnings. Just imagine if BRK merged with Coke someday (i.e., owned 100% of Coke). BRK (and its shareholders) would have a rightful claim to 100% of Coke's earnings. The same is true if BRK only owns 8% of Coke -- BRK's shareholders have a rightful claim to (and actually own) 8% of Coke's earnings. It's a transitive relationship: if BRK shareholders own BRK (true) and BRK owns 8% of Coke (also true), then it must be the case that BRK shareholders own 8% of Coke.