I did a little checking into the story, and wrote an update to "Golden Tridents on Petty Officer Michael A. Monsoor's Coffin" (July 5, 2008).
The bottom line is this: the video (embedded in the original July 5, 2008, post) shows SEALs approaching an essentially stationary coffin, and carefully placing each trident, before pounding it in place.
A lesson here may be to take a closer look at available evidence, before declaring something to be a hoax.
Update, of a sort:
- "Navy Petty Officer Mike Monsoor and the Trident Hoax"
(March 11, 2009)