If there's mysteries introduced in an episode, they'll speak about it a bit in the spoilers with regards to where it goes. But, they put more emphasis on the non spoiler talk, as there's a lot of people using it as an accompanying podcast for their first watch. They do start adding more recurring bits in spoilers. I will add that they get some really good interviews during latter half of season 1, including writers and other key crew. They also get Jorge Garcia and Lindelof.