I think it's because while on the job you cut corners and everything. You don't, and often can't, use proper technique. In the gym, barbells are perfectly symmetric and balanced. On the job, you might carry something that forces you into a horrible posture. That can't be good for you
It's not a typo. In Italian, we call the nineteen hundreds the nine hundreds in speech. So when we write it, we use '900s. As 900s without it would be the actual 900s
I suggest to use the browser even on phones and tablets. Once you get used to YouTube with extensions you realise how aggressive and enshittified the app is