If you put the same signature on your photos as the one you put on bank checks then you're asking for trouble.
That said, everyone can follow the steps provided in the yt video and make their own, custom signature watermark. The key here is being creative and designing something unique to you, for you. If you have a pen, a sheet of paper, and an DSLR then you can do this yourself.
But if everyone starts doing this, then it is no longer really unique... it's at trend. People sell trends. This is a trend.
If you are OK with that, then go for it. I think it looks pretty snazzy for what it is, but there is an element to this that still seems off to me. Companies pay big bucks for custom branding. But the branding is generally very unique to the company. This is not that unique; They all look pretty much alike -- a cursively styled signature and the word 'photography.'
I don't go out to eat because I can't cook myself. I go out to eat because I'm either wanting to forgo cooking duties and enjoy the evening, or I'm out in town and it is inconvenient to go home and cook and then come back to town. What I eat doesn't uniquely market or identify me in public. Plus I eat daily. The same doesn't apply here to these watermark sigs. This is a one time process and there is literally a video that goes step by step through the process.
If you want to spend money on it, be my guest. It is your money and they are your photos. But you don't HAVE to, to get the same effect. Every photographer has the tools to do this at home and is capable, creatively, of making one of these!