It depends very much on what your channel focus is now. If you are a "sit and talk" kind of vlogger, then there are tons of facts about St. Valentine and Valentine's Day as a "Hallmark holiday" that are really interesting.
If you go out and do things with your camera, maybe you could go to all the stores that are heavy on Valentine's Day stuff and check those things out, maybe talk to store clerks about what VD is like, and when the rush is, etc.
If you do comedy, you could do some sort of skit about missing Valentine's Day, getting presents at the last minute, etc.