It's infamous for trying to sting the Washington Post with false rape allegations.
https://en.wikipedia.org/wiki/James_O%27Keefe#Failed_attempt...
Project Veritas is the name of the organization run by this guy: James O'Keefe. His modus operadi is to set up some sort of meeting with a liberal target under false pretenses, secretly record video, and then edit the video as much as possible to make them look bad. He made a name for himself doing this to ACORN back in 2009 (which successfully destroyed ACORN but also led to O'Keefe later paying the poor defamed ACORN worker $100,000).
When I say "criminals," I mean he and his employees pled guilty to disguising themselves as telephone workers and sneaking into the office of a U.S. Senator. https://web.archive.org/web/20100531174024/http://neworleans...
Examples of his recent work include having his employee try to convince the Washington Post that Roy Moore raped her, for the purpose of discrediting the Washington Post's other stories about Roy Moore.
They've been front page news multiple times for doctoring videos, lying, etc. The acorn "sting" and WaPo incident are probably their greatest hits.
That said, I don't think "taken with a grain of salt" takes it nearly far enough. Project Veritas is not an unreliable news source. It is a propaganda agency led by criminals. I don't know of a single completely true news story ever produced by them.
Beginning an argument with the antecedent "If Project Veritas is telling the truth about this" brings us into the realm of fun and fancy. If someone said "If unicorns are real and produce large quantities of greenhouse gases, then man man may not be responsible for climate change," it'd be a reasonable logical statement, but it's still not useful in a serious discussion about anything.