Anonymous source (already had found the vid) with a CLAIM.
The STATIC pictures do NOT prove/show/or even indicate that is 'not that difficult'. They provide not a single hint of how long it took to remove those 'missing' panes, how many people were involved, what machinery/tools were required, nor how long it takes to put them back in and reseal them.
Removal for CLEANING- extremely dubious claim. Again, safety issues (especially wind resistance) require not only a STRONG SEAL (extremely strong - even moderate winds on that large a surface area create mega-loads), but also an AIRTIGHT and WATERTIGHT SEAL.
As for ranking the credibility of the claim in that video by an anonymous source - gotta go with about a ,01 on a 0-10 scale.
Finally, brethren, whatsoever things are true, whatsoever things are honest, whatsoever things are just, whatsoever things are pure, whatsoever things are lovely, whatsoever things are of good ...