Aaron's wedding photographer lost half his wedding photos. Leo says job one of a wedding photographer is to never lose the pictures. Aaron does have HD quality video of the wedding, and is wondering if he could get stills from that. Leo says yes he can, but he shouldn't get his hopes up that the quality of the images will match the actual photos. He can take a snapshot as he watches it if the video is on his computer. Leo recommends VideoLan VLC Media Player. Quicktime player would work as well.
This is a prime example of why a good backup strategy is crucial. Leo recommends the "3 2 1" backup strategy that can be found at DPbestflow.org. This is geared toward photographers but is good backup advice for everyone.