Rachel answers an age-old grammar question about was and were. Old grammar rules stick in our minds like chewing gum in the hair. The rule you remember is no longer a rule (perhaps it never was) but a choice. Rachel tends to use ‘were’ out of habit, but 'was' is now more than acceptable—it’s the norm.
We could (and we often do) explain the difference between 'you're' with an apostrophe and 'your' without an apostrophe. Many, many people trip up on this pair of similar words. If that includes you, each time you waste a few seconds thinking about it. Or looking it up. Or using a grammar check, and wondering whether to trust it.