Hi
I had a look at this problem with VP 10.24 32 bit.
The original clip from Borate was a 283 Mb mp4 with a duration of 0:24:18.869
Using this full 24 minute clip the Sequence Preview at 6.508 showed the footprint frame.......

The Snapshot of this Preview frame was correct...

The snapshot feature here is working correctly. What did you get displayed at this value?
You wanted the campsite frame and you quoted 19:02.099. This produced this Sequence Preview window..
.
and a snapshot.......

Conclusion here is that again Snapshot is working correctly.
The campsite frame however,(as mentioned and shown in Borate's) is at 19:01.996...(see below) This is one frame previous to the above frame with the tree........

The snapshot of this Sequence preview is also correct...

Again conclusion is that nothing seems to be amiss. Except perhaps your frame times. What appears in the Sequence Preview display is correctly snapped.
Are you certain that you didn't step a frame (or two) forward when you made the snapshot?
Nat