Also, several of the tomato seedlings that I had transplanted were leaning over:
One thing that this video taught me is to plant seedlings low in the cup, so as they grow and get taller, you can add more dirt. The other important thing I learned is that it is important to keep the seedling as straight as possible - so it will grow upright and be strong. So, I re-transplanted some tomato plants, and then I did a bunch of tomato seedlings, pepper seedlings, and eggplant seedlings.
I feel bad that I am resorting to plastic cups and not recycling old newspapers, but this saves me a lot of time and I like this system better. Plus, the cups only cost 4cents apiece.