Nowadays, you can print guns out of basic PLA. At least in .22 caliber, I don’t know about anything larger, though I do know 3d printed Glock frames are definitely a thing. A 3d printed suppressor is definitely feasible, as I’ve seen at least 1 design for PETG.
Now, as to whether or not that’s what can be seen in the video? Who knows. I certainly can’t tell.
His family proved in court that the government killed him, but every judge in criminal courts refused to let the case go to trial, so it was only a civil court case. But the judge was convinced by the evidence and found the government guilty and dues were awarded.