Pretty sure the issue was not the selected code of 123456 that was used in the video as an example. It would not matter what code the person took, it could be any of the one million different codes.

The issue is that the default code every one of those safes ships with, the 000000 one still opens it, no matter what number you enter as your personal code. If the hotel does not change the default code on each safe to something else, whatever code you put in makes no difference.

The thief doesn't need to try 123456, they don't need to use any kind of machine, they have to go to the keyboard and type in

zero
zero
zero
zero
zero
zero

and it will open because many hotels don't bother changing the default admin code to open it when a guest forgets their number.

I would guess with all the publicity this has been getting in the past few weeks many hotels are scrambling for their manual to see how to change the code.

Or as one of the makers of Hotel Safes has said after this story went viral

When a guest forgets [his or her] code, the safe may be opened by hotel security using the override code.

It is important to note that only the most negligent of hotel operators would leave the override code set to all 0′s, a default code, some other easy to guess code. The override code can (and must for obvious reasons) be changed to something difficult to guess prior to putting the safe into operation.