Jonas was absolutely appalled when he watched the video of the release. He couldn't believe that release, which was portrayed as this wonderful thing, was really just killing. He was also devastated to find that his father had been doing this and lying to the family about it.
As he watched it happen, he felt like he was choking and he flashed back to the memory the Giver gave him of the dying soldier. Then he starts to cry and yell.
After he watched the video, he was so upset that he did not want to return home that night and spent the night with the Giver.
Once he calms down a bit, he starts thinking about how no one else in the community has feelings. It is at this point that the Giver starts to think about having Jonas escape from the community.