I checked on them daily from start to finish! A couple of days before they fledged, a small branch had fallen on them. I oh so carefully removed it only to have the babies jump out. Their coloring made them completely invisible; they totally matched the ground with its leaves and rocks. I was really overwhelmed as to what to do. I knew I could not move my feet! But I gathered my wits about me and without moving a foot, found the first one and put it back in the nest only to jump out again. This time I put it into an empty clay pot I happened to have handy, one that the little bird could NOT jump out of. Then I proceeded to look for number TWO. He/she had gone into a storage area and had attached itself to the spokes of my son's bicycle. I carefully removed it and put it into the clay pot with the other little bird. I needed to compose myself and figure out what to do next. The nest was at the end of a very scrawny branch about 5 and a half feet off the ground. So I decided to put a 4 foot ladder beneath it and then on top of the ladder I put a very large, probably 24 inch, plastic tray for a large potted plant. (See the picture below.) Then I put the babies back in the nest together. They were hugging each other and this seemed the best way. They were fine for a bit and then one did jump out again but ended up in the tray, so I was able to put it back right away. MOM never skipped a beat. I know there are tales of birds leaving their young if a human touches it, but apparently hummingbirds do not have a sense of smell. So even if that were true, it would not have affected this situation. The babies remained in the nest from then on until they fledged 3 days later. MOM continued to feed them after they left, up in the trees for a couple of days. I do not know if they have ever returned.
Here is the tray. If you look directly above, you can see the babies.