Yeah... Spartans are no where near that fast, very few things are. Spartans are only slightly faster than an average human in armour, Space Marines can move faster than that and can certainly visually track faster than that.
Where as spartans being too fast for a space marine to track is a bunch of shit, in the books, they can indeed run much faster than normal humans. They are capable of running about 55 km/h outside of their armor with Kelly being able to run a little faster. Inside their armor, their movement speed is increased. Kelly's increased to 62 km/h. In a training exercise (where his life was put on the line because of a jackass admiral wanting to truly test out their abilities and hopefully kill him in the process), John was able to briefly run at 105 km/h but tore his achilles tendon because it wasn't able to endure the stress.
Being too fast for a space marine to track? Yeah, no. Being able to pick up a baneblade... Well, look earlier in the thread and you'll see me dispute claims of them being able to flip 72 ton tanks with ease simply because its a game mechanic that was introduced to make life for a player easier in MP games. After all, people flip their vehicles over all the time in MP. Wouldn't it be a bitch if you couldn't flip them back over and continue to use them? In the books, Master Chief has a bit of trouble simply flipping a warthog over.
Elites movements. Where as they do have faster movements than normal humans, Lux is just greatly
(heavy, heavy emphasis on greatly) over exaggerating... again...
But then again, there is no reasoning with him. Simply can't be done.