According to the caption, this was
YouTube/Official STAR WARS channel…the original teaser trailer for Revenge of the Jedi, which appeared in theaters before Star Wars creator George Lucas changed the name of the film to Return of the Jedi. This trailer features the completed Revenge of the Jedi logo, shows Luke wielding a blue lightsaber (in the final film, his Jedi weapon would have a green blade), and features a quick shot of Obi-Wan Kenobi before “spirit” effects were added.
Related: in addition to not being called “Revenge of the Jedi,” studios codenamed the movie that we know as “Return of the Jedi” as “Blue Harvest” to keep the storyline and production process under wraps from Hollywood snoops.
And that’s your STAR WARS history lesson for the day, kids.