Not only could you abuse the trooper exactly this way, you could also chuck your saber right into his chest and bash him in the head with an entire vehicle (even an AT-ST, if you're strong enough) before launching him off to his doom just as your saber sears its way back out from his torso and returns to your hand like a laser-powered boomerang.
In fact, even some of the subtler things you've seen in the video will happen. Your enemies are smart - and often scared of you - and they really will flail their arms about, trying to grab onto heavier objects in the environment hoping to save themselves. And the various materials will behave (read: break apart) just as they would in real life. In other words, metal can dent and warp, wood can splinter and fracture, glass will shatter, etc.
Above: These images are all concept art, but we actually did see the game up and running impressively on both 360 and PS2
So, why is Vader's right-hand man killing s tormtroopers? Because of the story, which is being written by Haden Blackman and overseen by Lucas himself, who considers this a fully-fledged entry into Star Wars canon. You're a secret. So, while you'll usually be pursuing noble Jedi (and possibly Maris Brood, who wields tonfa-sabers in her concept art), that's not always the case. For instance, when you pursue a Jedi named Kota to a massive space station that's actually a TIE fighter factory - a level we saw fully playable on both 360 and PS2, by the way - you can leave no survivors whatsoever, regardless of whom they serve.