This isn't just paying in cash. There are a lot of vaguely suspicious circumstances in this video. For example, his ID is stated to feel wrong. The video even mentions a list of warning signs, like appearing nervous.
And looking at the environment, that's not some shitty little motel. I think its a four star hotel at the least. Even staying a few weeks at a Motel 6 would add up to a couple hundred or even thousand dollars. Staying in a nicer hotel would probably add up to several thousand dollars. And paying several thousand dollars in advance, IN CASH, is odd. Who carries that much in cash?
If you were to mug me, you'd be lucky to get 100 dollars off me, assuming I even had cash. I don't have a credit card, either. But I do have a debit card. Paying with a debit card is basically the same thing, but less suspicious.
Admittedly, the video is a little odd and borders on fear mongering, but I don't think it is that bad. You're kinda taking it out of context.