Comparative Advertising is defined as when advertising, a "company directly or indirectly compares its brand with one or more other brands" through the textbook. In the one-minute ads, PEPSI directly competes with Coke on the same stage. The two men are quite friendly to each other and not differentiated until the scene comes to PEPSI and Coke. The "PEPSI" man tastes Coke and thinks it is a way worse than his PEPSI; the "Coke" man takes PEPSI and does not want to give the can back. Then PEPSI man becomes angry and punches the Coke man to "territorialize" back his PSPSI can.
The message PEPSI is trying to send is that PEPSI products are unique and there is no alternative. Another message is that the major competitor of PEPSI, Coke, is way worse than PEPSI. It is typical comparative advertising; even more PEPSI directly compares its brand with another brand, Coke.
However, the effects to do so may not be as good as expected. First, consumer reflection. Since PEPSI and Coke are really not very differentiated from each other; some consumers even can not distinguish them. The strong message PEPSI tries to send about the strength of PEPSI does not really let comsumers agree on that. Not all the consumers prefer PEPSI over Coke, even more people likely prefer Coke since Coke seems to have more market shares than PEPSI. This ads might not have the effect that acquires "neutral" consumers and weakens Coke consumers' loyalty; conversely, Coke fans may reflect very negatively and drive themselves more far away from PEPSI products.
Second, comparative advertising like this ads may cause the two competitors to produce campaigns that attack each other. Too many negative elements are not appropriate to be applied in ads because consumers would get tired and leave both of the two alone if PEPSI and Coke keep insulting each other and revealing some factors neither of them ever want the public to know. That is the reason why firms should be careful about comparative advertising.