Lord Farringdon - I actually asked myself that same question. And then gave it further thought.
And the conclusion I came to is: that the NTSB takes a methodical, organized and scientific approach to investigations. They aren't going to go haring off after any particular piece of evidence until they have collected all the evidence (and it appears that, at the time of the video, half the aircraft more or less was still out in the mud.)
It's my impression (with no direct experience) that the NTSB first and foremost sets out to determine exactly what happened - relying on evidence such as the videos and track data and coms we've also seen and heard, and also things we have not seen and heard here (FDR and CVR recordings if available; actual radar returns; impact pattern(s), witness descriptions, clock times, and so on). And only once they are sure they know what happened in detail, move on to investigating how and why it happened (which is where the physical jackscrew will - or won't - come in). At which point they will go over to the hangar where the parts are stored, and start testing any and all theories that have developed, against the physical evidence of aircraft parts recovered. As well as sifting through maintenance and crew records and other specifics.
Of course, at that point the physical evidence may suggest additional ideas, and the investigators may go back to the tapes, to see if there was an anomaly (sound, crew comment, control movement or disparity) that went unnoticed on the first reading.
In short, at this point, nothing "figures highly in their minds" - or doesn't "figure highly in their minds," one way or the other. The jackscrew isn't going anywhere - it can wait.
cf: "confirmation bias" - and read your Thomas Huxley: "Sit down before fact as a little child, be prepared to give up every conceived notion, follow humbly wherever and whatever abysses nature leads, or you will learn nothing."