The Awesomes
Season 3: Villain-Tine's Day (Hulu; IMDb; TV.com)

Childrin R Skary
2009: Cupid's Last Stand (YouTube)

Grimm (TV series)
Season 3 webisode: Love Is in the Air

Grumpy Princess Show
2016: Reading my Mail (YouTube)
2017: How to get All The Princes (YouTube)
2018: How to treat a Princess (YouTube)

Into the Dark
Season 1: Down (Bloody Disgusting; Hulu; IMDb; PopHorror; Wikipedia)
Season 2: My Valentine (Hulu; IMDb)

Life Hacks for Kids
2016: Hacky Valentines! (YouTube)
2017: Hooray for V-Day Valentines Hacks (YouTube)
2018: Upcycled Valentines Hacks (YouTube)
2019: Hacky Valentine's Day! (YouTube)

SciShow Kids
2023: Valentine's Day at the Fort! (YouTube)

SciShow Psych
2020: Valentine's Day Is Bad for Relationships (and That's a Good Thing) (YouTube)

Underlined
2020: Monthly Must Haves: February 2020 (YouTube)
2020 also: Find Your Next Love Story (YouTube)

Written by a Kid
Season 1: The First Valentime's Day ...That I Don't Believe! (IMDb; YouTube)