I have one advantage over Bridget in the exercise department. I can watch Bridget Jones's Diary while running on my treadmill, and she cannot.
Here are some factors to consider when picking a good run-on-the-treadmill movie:
(1) Expected length of run. You will surely quit running the second the credits roll.
(2) Pacing. If you're doing intervals (which you're insane if you're not), you want the story beats to have a similar interval length. Preferably something that accents these story beats with music and/or musical montages. (I'm Every Woman montage at the midpoint is IDEAL!)
So, when I'm running for 1:40, Bridget Jones's Diary is a perfect 10.