Can you view the seat availability before you make a booking? It seems to me that you have to purchase your flights first, get a reference code, before you are allowed to see availability?
AFAIK yes it is possible to view the seat availability before you make the booking using the option above. I certainly did a booking quite some time ago and was able to see the availability beforehand.
I regularly look at options and view the seating available. I rarely travel because I'm a bad traveller and I'm also too lazy. When 'beam me up Scottie becomes available I'll go then