Joss Whedon is currently working on the next Avengers movie, but being entrusted with one of Hollywoods biggest franchises hasnt stopped the creator of TV shows Firefly and Buffy the Vampire Slayer from experimenting with smaller films and new distribution models. Whedon, who appeared on video after the premiere at New Yorks Tribeca film festival to confirm the worldwide release, explained the choice to put the film up for rental online.