That was entertaining and hilarious to watch.
Some gamers tend to forget that not everyone thinks the same way, and that things that may be obvious to those of us who are more advanced gamers may not be so obvious to more novice gamers. Even further, not everyone, including gamers, has the same level of skill in gaming, and not everyone can play every game with equal facility. Some things are just difficult for some and, yet, easy for others.
The Dad is obviously an intelligent guy, but his framework of logic seems rigid and strictly procedural(generalizing rules and patterns is not a natural process for him). A game like Portal requires a much more flexible logic framework, hence the level of difficulty he experiences trying to solve the puzzles. The type of thinking he has to use in the game is completely new and alien to his normal thought patterns. He has to learn a whole new way of thinking, and that can be difficult, no matter how intelligent a person is.
Many adults experience exactly this problem. After a certain age, for many adults, thought patterns, logical frameworks, and conceptual frameworks become frozen, and it is difficult(but not necessarily impossible) to learn new frameworks that challenge or usurp the existing ones. As adults, we become set in our ways because we have invested a life-time of learning those things which we know, and we become comfortable with the certainty of those concepts. Having that certainty disturbed is a frightening prospect because it means that the world becomes dangerously unpredictable again.
Avoiding this frozen state is something that has to start at a young age, while the brain is more plastic in nature, and has to be continuously cultivated throughout adulthood. You have to continuously challenge your mind with new ideas and concepts, and you have to work to apply and generalize those concepts to situations and contexts beyond that where the ideas and concepts were learned. In essence, you have to consciously work to keep your mind open. One has to constantly be prepared to throw away everything that is considered true in order to learn the new way. To use a Biblical reference, your mind must be that of a child to enter into Heaven. This doesn't mean you be immature; it means you have to remain open to concepts and ideas that are foreign to all your prior experience. Remember that nothing is necessarily true, not even this statement.
(Sorry, the ramble process started up again)