[gunsequalfreedom]

I just watched the video. Has me convinced unless there is some explanation. Hard to believe someone would not flatten the document before creating the PDF. Me, I would have put it through a few more gyrations even after flattening it.

It is a real good Photoshop job though. Clipping around a signature is tough and it looks like they did an expert job at that.

[edge919]

When you build a document in a program like InDesign and export it as a PDF, I don’t think flattening is an option ... or at least it’s not an obvious option.

[visualops]

Clipping around a signature is tough

LOL no it isn't.
A very good graphics person can merge documents and images nearly flawlessly. The only impediments are source material, time and talent.

Anyone who was forging a document and did stuff like not flatten the image, not pay attention to differing source material resolutions, shadings or patterns is either an amateur, in a big hurry, or simply knew it didn't really matter whether the job was any good or not.