Remeber this video is mostly based on novels in the previous expanded universe and from video game sources. So ultimately means squat in the movie and new canon universe of Disney. Lucas never went on record as ever saying what the colors meant (nor has Disney up to this point). As in that video there is much information contradictory as to what we've seen in the movies. In the clone wars episode with Yoda & the Padawans making their sabers, the crystals called out to them. They didn't pick the color nor was it assigned to them as some sort of rank nor based on their abilities. Also Yoda & Mace Windu (who also created his own lightsaber fighting style)are regarded as the most powerful/proficient living Jedi saber wielders (with Anakin, at the time, closing in). And as stated, Samuel L Jackson just wanted a purple lightsaber cause he thought it would look cool, and he never even thought Lucas would actually do it... That was it, no other meaning... So as of now, colors mean squat, other than the Sith/Dark Side devotees using red synthetic crystals.