I may have already posted this...
A few years back, my wife and I went with some friends to Glacier National Park. One day, it was just a friend and my wife and me hiking. We started by hiking to Iceberg Lake then came back and took a trail to Ptarmagin Tunnel, which was an actual tunnel (200' long, I believe) cut through a mountain. I had been to both before, but it was their first time. We were maybe eight miles into the hike, heading up toward the Tunnel, chatting away, when we came around a corner and bam, right in the middle of the trail was a grizzly bear and her three cubs. I would say they were 30-50' ahead of us on the trail and slowly heading the other way. When I say "cubs" they were still huge, with their back maybe almost as high as a desk. The mother, of course, was bigger.
We froze in place. My friend, who is usually extremely talkative, went silent. My wife covered her eyes (she said) and I began fumbling for my camera. Instead of grabbing my digital camera, I grabbed the camcorder, whipped it up and started recording. As I did so, one of the three cubs, turned toward us and stood up on his back legs and sniffed. Moments later, he dropped back to the ground and they continued away from us on the path. I honestly can't remember if the mother or other two cubs ever actually saw us. We waited a few minutes. My wife said something to the effect of, well I guess we have to go back. I told her we'd just wait until someone came toward us on the trail. Then we'd know the bears were gone. We actually didn't wait that long and started walking up. The bears had headed off the trail somewhere and we never saw them again. We did see some people coming down but they never saw the bears, so it was all clear.
We finished the hike and rejoined our other friends, anxious to tell them about the close encounter. We knew they'd never believe us, but we had video proof! So, back at the rental cabin, having already told them, I pulled out the camcorder and was flipping through the recordings (it's the kind with a hard drive and you can view each recorded clip.) There was no bear footage. The only video I had from that section of our hike was of the ground. I couldn't figure out where it had gone. This wasn't a lens cap thing. I could see everything I was recording on the screen while it was happening.
Then it occurred to me what must have happened. When you turn this camcorder on, there is a delay of a few seconds before you can start recording. Kind of like a boot-up period. Well, I quick-drawed it like someone in a high noon shootout, pressing the record button immediately after turning it on. So, while I could see the bears on the camera, it wasn't actually recording, it was in the default "pause" mode because it hadn't accepted my pressing the button. Then, when I pressed the button "again" to stop recording, it actually started recording and I had brought the camera down to my side and it started recording the ground as I walked.
In the end, the friends did believe us, because my wife vouched for the story and the others knew she wouldn't make it up. But I still to this day berate myself for not grabbing my digital camera. That cub standing up was like something out of National Geographic...