Investment banks might actually lose money in recessions because they might take illiquid, toxic assets onto their books to service demand (point and case: the mortgage crisis). And securities is only a part of the investment bank business model. Advisory services, largely driven by M&A and IPO volume, provide a decent chunk of profits for banks. Capital markets dry up during recessions, which will completely stifle M&A and IPO activity and therefore revenue on that side of the bank.
This guy is full of shit. When asked what to invest in when the market goes down, his best advice is bonds and "hedging strategies". Bonds do indeed rise in value during bear markets, however hedging has almost nothing to do with profit or loss. Hedging is risk management: covering your ass in case of an unexpected move. For example, if I expect a downward market turn, as per his advice, I might buy up treasuries. But, to "hedge" the possibility that the market moves UPWARDS instead, I might buy an index tracking the Dow, which will increase in value as the market moves up. In this case, hedging is actually DECREASING my profits in the case of a downward movement in the markets. There are much more intuitive ways to play a downward market.