Realize that Sal recorded this video in March of 2008, at the peak of the housing bubble. Many of the assumptions made in the video are certainly not going to be the same in today's market.
When you're modeling the rent vs buy scenario, the outcome is hugely dependent on regional factors (like average rent & purchase prices in your area), current economic factors (like mortgage rates), and also your estimates of future events (like long-term investment return, rental price growth, and home appreciation). Even small changes in these factors can make a huge difference in the outcome. If you're interested in going into more detail, I suggest downloading the model [1] that Sal was using for these videos and plugging in your own numbers:
When you're modeling the rent vs buy scenario, the outcome is hugely dependent on regional factors (like average rent & purchase prices in your area), current economic factors (like mortgage rates), and also your estimates of future events (like long-term investment return, rental price growth, and home appreciation). Even small changes in these factors can make a huge difference in the outcome. If you're interested in going into more detail, I suggest downloading the model [1] that Sal was using for these videos and plugging in your own numbers:
[1] https://www.khanacademy.org/downloads/buyrent.xls