Hamas is sending a message to Palestinian rivals

As Israelis and Palestinians celebrated the ceasefire in Gaza, a video made the rounds on social media. It appears to show Hamas gunmen executing a group of eight men in the street in Gaza City, accusing them of being criminals and collaborators with Israel. There have also been gun battles inside the Gaza Strip between Hamas and rival groups. One expert says Hamas wants to reassert its control in the territory and send a warning to any group that would challenge its authority. The World's Matthew Bell reports.