Mom vs. mom

P&G's current ad campaign ends with the frame above. Moms should not be capitalized because it follows a possessive pronoun.

When the word mom is used where a name could be substituted, it should be capitalized.

I told Mom about my dinner plans. (I told Sarah about my dinner plans. This would work.)

When the word mom follows a possessive pronoun, it should not be capitalized.

I told my mom about my dinner plans. (I told my Sarah about my dinner plans. This would not work.)

This rule applies to other words such as dad, grandma, and grandpa.

Upon finding the commercial online, I was dismayed to see the misspelling of commercial on the website.