In order for an app to do that it would have to be set to record on a loop and only make a seperate file when it captures motion. So regardless you would have been recording the session (unless you bone perfectly still). That coupled with the fact of the deliberate angle and specifically the fact that you noticed your pants (phone) had been moved as stated in the original post, means that you were not completely innocent either.
And no I am not defending their actions. Taking money out of someone's wallet pocket etc... is wrong - no excuses. And I too tend to take more in with me just in case, but I hide my extra stash somewhere else.
I actually appreciate you informing us of what had happened, and supplying the video evidence. But which app do you use - I have seen similar ones but they record either 30, 45 or 60 second clips not 34 seconds.