My $0.02 - this might be the wrong way to address the 2 biggest risks (cleaners stealing, cleaners not working). For me, by drawing so much attention to these items you're basically saying "we don't really trust the cleaners, and neither should you, so let's monitor them".
And then there's the question of who actually watches the video? The customer = more work for them. You guys = not super scalable.
What about privacy? What if the smartphone captures something super sensitive out on someone's desk (e.g. a major contract)?
The final point is that your competitors could just say "Ya, we actually just hire good, trustworthy cleaners so we don't have to bother with spying on them (and neither do you). Here are 10 customer testimonials that proves this. Those spying guys probably just hire really shady people and need the spying to keep them in line."