Recaps are recaps and usually dont add anything else besides from the info that has already been given in the main series.
These recaps are sligtly different in the sense that they provide background information.
Who the characters are, in slightly more depth, information on the tanks and tankwando etc.
The first episode is meant to watch after episode 5 on the main series. And ep 2 after 12.
For example in the main series I wondered why tanks didnt get destroyed.
In the recap they said that every tank has a black box, and every shell on every tank has a tracer. The black box calculates the damage based on position of impact, type of shell etc. And after critical damage, the tank shuts down (in case it was still operating ;) ) and the flag pops out.