Hey Justine, I adore that KPC premix as well and really like mixing legs and cardio, so you motivated me to search for the leg/cardio premixes! Besides what was already mentioned, here's what I could find:
Athletic Training - Leg Cardio Express premix (35 mins)
Boot Camp - Cardio and Lower Body premix (34 mins)
CrossFire - any of the premixes with firewalker tabata
Drill Max - Cardio Leg Blast (like firemedic, this is a personal favorite!) (57 mins)
High Step Training - Cardio and Lower Body (26 mins)
Kick Max - Cardio Leg Sculpt (52 mins)
Low Impact Circuit - Lower Body Circuit (56 mins)
Low Impact Step - Lower Body Cardio Blast (49 mins)
On those days when I have the patience to switch between different DVDs during my workout
, I will do the leg portion of a total body workout (like MM, ME, MIS) or a shorter leg premix (B&G, LL, GG, etc) and then combine that with a HiiT of my own creation or a shorter Cathe cardio premix.