These churches are doing something different: They are posting videos and podcasts of their Sunday sermons immediately after the service. This allows their members to leave a comment or ask a question after the service.
People who are touched by the service can share it with their friends and family members. This is much better than just pushing out a video or podcast.
Use your imagination and understand why social media works. Also, remember that content that comes from friends is much more likely to be viewed than content that comes from a church.