The expansion looks good but I still see a few problems with it:
With a 50% increase in passenger numbers, if not more, the terminal may only get busier even with the expansions in place.
The new entrance will take the place of existing bus stops. With more passengers, there will be a growing demand for bus/coach transport, yet there will be less space for buses directly outside the terminal than there currently is today.
There is no improvement on car parking. If anything, that may also decrease with the new two-story pier so car parking will become a lot more restricted.
There is no mention of the departure lounge, just an increased amount of seating. Perhaps it just wasn't mentioned in the video, but an increased range of shops, restaurants, food outlets etc. will also be needed to cater for more passengers as well as more space.
The fundamental problem at Luton is the small amount of land they have to develop on. It's already fairly small and compact as it is. Despite the widening of the road from the Holiday Inn to the Terminal, traffic congestion may still be a problem right back from the M1 and for people in Luton itself.
It would be good if it all happens, but I would be hugely opposed to it if I were a resident anywhere nearby.