I spotted the groundhog near my garden again today, so I called my wife over to film my shot. By the time she found her camera and came to the room, the groundhog was no longer to be seen. It had been heading for deeper grass though, not for its burrow, so I thought it was probably still there. I suggested she go onto the deck and film from a chair, which she did. Then we waited... and waited... and waited, but the critter didn't show itself again.
Eventually I told my wife that I was giving up. She decided to stay a bit longer, so I passed her the rifle and told her to take the shot if she could. She's a better shot than I am, anyway. I walked away for a few minutes, then returned with my camera and stood by the sliding glass door watching.
A bit later, I saw its brown head in the grass. I wasn't sure that was actually an animal, but it disappeared again so I knew that's what it was and that it was still there. I told my wife where it was and that she'd have to stand to see it. She did, and then spotted it. Here's my video. It's the brown thing next to the large flower pot.
http://www.youtube.com/watch?v=vQYuClm4q5A