White label Beam is 80 proof and Larceny small batch is 92 so it seems strange that Beam would evaporate since its a 6% different alcohol content. If you normally drink barrel strength 120-130 proof stuff I could see it. Bad seal on the decanter lid maybe?

Laws can vary but generally video recording is allowed in US states except in private areas like bathrooms and changing rooms. Audio recording laws vary by state laws (single party consent). In most offices it is normal to have cameras watching doors and common areas but not individual workers.