Taken from the first episode called 'Sympathy for the Devil', the clips show changes in relationship between Dean and his brother Sam after the Devil is accidentally released by the latter.
More scenes from the season premiere of "Supernatural" is released, showing the first fight between Dean and Sam after the latter broke the seal. Sam keeps apologizing to Dean about what he did but Dean is angry because Sam keeps bringing it up instead of cleaning up the mess. The brothers then agreed to work together in bringing down the devil.
In another clip, Chuck the Prophet mistakenly strikes Sam with a stick because in his vision the Winchester is looking nothing like normal. Chuck then delivers a startling message about Castiel, telling the brothers that the angels have exploded him into pieces. Also, Zachary talks some sense into Dean that the Apocalypse is now, and that they must work together to stop it.
It is believed that the fifth season will be the last of the series. Creator Eric Kripke said he didn't quite expect to see it beyond five-season storyline but never excluded the possibility for another one too. "That doesn't mean there can't be a new story. Buffy did it. The X-Files did it. You close a chapter on a big mythology storyline and then you begin a new one," he explained.
The episode called "Sympathy for the Devil" will kick off the whole season 5 on September 10.