I don't have a definitive answer for the appearance of the explosion in this incident, but a few things are worth noting:
Note the appearance of the first-stage engine plumes at 2:22. Rather than the bright dense yellow column seen at liftoff, the low atmospheric pressure at the rocket's altitude allows the exhaust stream to rapidly expand into a relatively faint, tenuous cloud. The rocket is still producing about the same amount of thrust (maybe somewhat less than at liftoff to control g-loading on the structure), but the exhaust looks completely different from kerosene/LOX combustion at sea level.
The incident occurred when a small high-pressure helium tank contained within the second-stage liquid oxygen tank broke loose, overpressurizing and rupturing the tank, as described in this Q/A. I assume the initial white cloud at around 2:30 is just oxygen release.
Once the second stage starts to come apart, kerosene is released as well, and you can see characteristic yellow-orange kerosene flame inside the white cloud at about 2:32 in the video.
You can see small pieces of the upper stage falling away from the rocket between 2:32 and 2:36 until the rocket comes apart completely. Two things to keep in mind here: one, the first stage is near the end of its burn here, and so largely empty of fuel; two, to get good combustion between kerosene and oxygen, you have to thoroughly mix the two. Starting with two separate "balls" of liquid venting into extremely thin air, you won't get good mixing; any combustion that does occur where the clouds meet will tend to spread the kerosene and oxygen further away from each other, so the majority of the remaining first-stage propellants just won't get burned here. That's why you don't see a large orange fireball here -- again, other rocket explosions you're comparing this to are probably low-altitude incidents, where atmospheric pressure is keeping the propellants from dispersing quickly. Additionally, according to the Q/A linked above, the flight termination system was activated, "unzipping" the tanks in a way that was intended specifically to minimize the force of an explosion.
At 2:38 you see several distinct pieces of the rocket. To me it looks like possibly 1/4 of the entire skin of the rocket is visible in pieces at that point -- remember that a rocket like Falcon 9 is basically a thin metal skin wrapped around fuel, not a solid piece of metal. So the big open question for me is where the rest of the metal went, but if it was being ripped into small pieces at about 2:37, those pieces could easily have gone out of frame while concealed in the vapor cloud.
Finally, I'm going to address the way your question here was initially framed. On this site we get a fair number of conspiracy theorists -- mostly moon landing deniers, but a few other kinds as well. I can't speak for the other regulars on the site, but they make me very angry; they waste our time and mental effort, and for the most part they aren't interested in truth as much as they're interested in propping up a paranoid world view. I'm happy to address any question posed in the frame of "I don't understand some phenomenon", but the same essential question framed as "This phenomenon proves some conspiracy theory" will never find a good reception here.
In this case, the idea that SpaceX would fake a launch accident simply makes no sense at all. They are still a young company trying to build a reputation for reliability; losing a rocket with a NASA payload hurts them very badly. Hundreds or thousands of people saw a rocket lift off, bound for the International Space Station. That rocket's payload never reached its destination, but it must have gone somewhere. In general, the simplest explanation for a phenomenon is, most likely, the correct one, while extraordinary claims require extraordinary evidence. "The rocket exploded as rockets sometimes do" is a very simple explanation, and "SpaceX faked a lost rocket" requires an awful lot of justification.
