There's no way to "Officially" debunk a Bigfoot video. There's no governing body that decides that, so really all you can do is apply logic and critical thinking, and hope for the best.

That said...

There are two main ways you can go with the argument that it is fake, and both are, I feel, equally valid.

• The Leroy Blevins Suit.
  • Leroy Blevins was a skeptic who did not believe in Bigfoot, and did not believe that the PGF showed a real Bigfoot. He set forth on a quest to prove that he could construct a Bigfoot suit that looked just as real as Patty. Parabreakdown DEFINITELY thinks it’s The Blevins Suit, as does Mountain Beast Mysteries.
    • Parabreakdown, Part 1: https://www.youtube.com/watch?v=7kb_QQmaRnU
    • Parabreakdown, Part 2: https://www.youtube.com/watch?v=ngP-ukw4Ss4
    • MountainBeastMysteries: https://www.youtube.com/watch?v=FZiBjN2_Vc4
    • Everyone breathe. Neither of these are the Zoidberg video, though it is referenced at the beginning of the first one.
  • The Squatchable Podcast: https://youtu.be/PsRsDObdRS8?t=1641
  • Blevins spent a year making the suit, and, as the story goes, went out and filmed this video to prove a realistic hoax could be pulled off.
  • The story, in the strangest twist you will ever read, was championed by Facebook/Findbigfoot. You know, the guys who never saw a shadow or a leaf or a suit they couldn’t find six points of confirmation on.
  • Blevins himself went on an angry, misspelled, and grammatically atrocious screed about this, claiming it wasn’t him, it was, in fact… wait for it, cause this is where everything just goes crazy… Facebook/FindBigfoot
  • They pointed fingers at each other until they got bored with it, and everyone moved on with their lives. (http://bigfootevidence.blogspot.com/2013/02/who-really-filmed-this-clear-video.html)
  • I admit, there is a lot here that backs it up as the Blevins suit. Parabreakdown’s second video, and the MBM video do a good job of pointing out the similarities (and there are several).