If only you could rent content...
I often rent movies from iTunes... love it when I bump into one of their 99c special rental offerings of something I have not yet seen. I can rent it and then buy it later if I like it.
More often I buy TV series I like to be able to rewatch on demand offline, and movies I've seen before that I want to have on my laptop rather than in cases of DVDs on a shelf.
Mostly now I stream stuff by subscription to Netflix, Film Movement (indies, foreign), Amazon Prime... but still tend to buy it later from iTunes if I like it and it's available for purchase.