It's part of Instagram's new (possibly controversial) support for full screen, portrait and landscape pictures.
More examples here
Instagram Video in Landscape - Examples from Instagram on Vimeo.
Follow that, Vine!
Good Examples of Digital Creativity and Media Usage including online advertising, web sites and search marketing. Compiled by Dan Calladine, Aegis Media - firstname.lastname@example.org All views expressed are my own. This blog currently receives about 150 unique visitors per day, according to Google Analytics. Follow me on twitter - I'm @dancall
A video posted by Star Wars (@starwars) on