Take Vans for example. They had a really relevant, interesting, funny Vine video for Star Wars Day. It didn’t say “Buy Vans Shoes!”, but it totally blended with their brand image. Delta’s is similar. It’s subtle but clear and relevant at the same time.
Then look at the Vitamin Shoppe’s post. It’s so forced that it actually hurts the brand’s image. So does Pillsbury’s.
The moral of the story is, make it relevant to your brand. Words and pictures for their own sake actually hurt your image.