I don't think that's the case. He indicated he saw Ahmaud leaving the house, not that he saw him on a contemporaneous video, access to which was in the hands of a neighbor living miles away whom he didn't know and his son had met once.
Thanks for encapsulating the leftist fantasy telling of this tale. The older man who was hoping to hold him up until the police arrived was a retired police officer who had investigated the young thug for theft, shoplifting and carrying a concealed handgun to school. The guy was put on probation for five years as a result of the investigation.
Though I don't know them there are several people on the sex offenders list in the towns I live in. They're on there because they've committed crimes, in the past. If I take it on myself to detain one of them at gunpoint, making a citizen's arrest, in the absence of a contemporaneous crime, I will have serious legal problems.
It is a little hard to cut through the BS on this because of all the slanted coverage. The son received an alert and video on his cell phone from the person who owned the house being built. He shared it with his father, the retired police officer who recognized the burglar from his previous encounters and investigation. This was not just two rednecks chasing down a random black jogger. That is why it took over two months of intense public pressure before the two were arrested.