I think the OP's idea is decent though not new.

Phantasy Star Online 2 uses a similar thing.
It currently have Episode I, II, and III.
Episode II is gated behind I, you have to finish I before you can advance to II.
But for Episode III, they added in a video digest of Episode I and II that you can watch (or hit the skip button) and go straight into Episode III. You can still go back and do the Episode I and II stuff later.