Nu, so someone can probably share what it is that apparently the velt is arguing with the video on specifically.
In short, the issues described in the video do not pasul the mezuzah. Some issues are problematic according to the Alter Rebbe, but there is plenty to rely on that they are kosher.
This is not from examining the exact mezuzahs in the video, but from experience checking mezuzahs from the same sources.
My issue remains that it is dishonest to sell such a mezuzah to a Lubavitcher without informing the buyer that it is likely not kosher according to the Alter Rebbe.