Ted is looking to replace his hard drive in his MacBook Pro. Leo has done that with all his laptops, replacing them with SSDs. It can be a challenge to replace the hard drive, depending on what model MacBook Pro he has. The modern MacBook Pros are a bit easier, although the screws are tiny and of difference lengths. Once he has opened it up, replacing the hard drive is pretty straight forward.
Leo gets all his Mac Parts at Other World Computing, at MacSales.com. Leo recommends an SSD. What about the Western Digital hard drives and the color categories? Leo says a Green drive would be a good choice because they're very low power, and MacSales has those. It's important to get the appropriate drive for his MacBook. That's why Leo recommends going to Other World Computing, which will guide him to the correct drive.