Do these need to start with a slingshot start? or can you start with a save from a previous level? Eg I've got an Episode 6 Hard 100% video, I started from a save at the end of 5-6

if you're doing single segment of all the episodes, then you can begin an episode with all the weapons, but if you're doing just an episode 6 run it has to start with the base slingshot.