The advantages are:
1) Doing something every day is easier. This eliminates the decision "will I run today?". Deciding yes requires more self control than doing it every day by default, because the choice has already been made.
2) Doing it for 2 weeks is low commitment, and sets a goal.
3) Doing it with someone else gives you outside pressure. This is good because you don't have to pressure yourself.
4) Running before dinner is good for two reasons. First you really don't want to run after you've eaten (hurts). Second, you don't have to remember it: your body will remind you (hunger: you want to eat so better get running).
Contrast this with: To lose weight I'm going to start running.
This is almost certainly going to fail. Now you have ask yourself the question "will I go running now?" at some point during the day. If this happens what will you tell yourself?
- I'm busy now; I will run later this day.
- My life is long; I will run tomorrow.
- The weather is bad now.
- I don't feel good today.
- During the run at 2km: I'm tired so I'm going to stop now.
Contrast this with: It's an hour before dinner. You don't even have to ask yourself whether you want to go running, because you already decided that you will. What are the excuses you can make up?
- You're not busy because you planned to run.
- You're only going to run for 2 weeks, you can do that.
- You don't want to lose the 2 week goal or the 3 days that you've been running already will have been for nothing.
- The other guy is ringing your doorbell/waiting for you, you can't say no to him.
- You don't stop after 2km because you said 10km. And the other guy is running next to you.
Eliminate decisions (do it every day, and 10km). Set a goal (2 weeks). Get pressure from other people so that you don't have to use up your own self control.
I think the key is not that you have to have good self control. The key is to avoid using it, and if you do have to use it try to make the right decision more preferable.
Oh, and two things specific to running/losing weight: you have a lower appetite after running (at least I do), and if you run you have another reason not to eat sweets/cookies/etc: you don't want to undo the hard work!