Interesting what they are doing with the technology. Soon we will have cameras on a tiny stick-on dot that would easily stick to a train nose or your child's shirt..
I guess the major advantage over the keychain cameras some folks here use is that this can transmit video to a device over WiFi.
I recall seeing one of these in use on YouTube but I can't find the video at the moment. The guy solved the clearance problem by strapping it to a flatbed pushed by a powered tender. Unfortunately, while that solved one problem, it created another when the unbalanced weight distribution caused it to sometimes derail on curves. It did eventually work, as I recall.