Big picture: It was brilliant marketing and a lot of fun based on the excitement in the media and having watched video. (I'll assume Sam Chui will soon post Part 2 with the LY 1747 flight and drawing ).
Other examples: A quick search will lead you to the final EVA 747 flight. Not as fancy, but nicely done.
As for passionate fliers and members of airline FFPs getting first access, I read the UA FlyerTalk thread on their final 747 flight SFO-HNL 2 years ago. Like El Al, party for staff and passengers at the gate, party onboard, also with custom menus and people in Hawaiian-themed clothing. And Oscar.
Regardless of security matters - which we can all assume were handled properly by all of them for their final 747 flights, it gave these airlines opportunities to allow their passionate customers, frequent fliers, staff and former employees to enjoy something. The added media coverage, whether by Sam or an individual onboard, really gives positive value to airlines and an industry more often on the receiving end of criticism (even if deserved).
While I am not a fan of the bloggers or many of Sam's videos, he has also showcased unique routes, and small regional airlines, some with interesting geographical challenges.