FURTHER UPDATE (June 5, 2015): I received this message from John, a biologist. I think this answers most of your questions. Thanks John!!
"Goodpasture had the answer in hand when he examined the nest and saw the thousands of mites. Both rodents and birds that reuse their nests have a chronic problem of mite buildup that can be fatal to the young. Both scavenger and parasitic mites can rapidly increase in the warm nest in a short time. And as the nest is gradually increased over time, more mite survive over the unused time. Mites will develop on organic materials available from both adult and young feces, bits of food, nesting material that may include adult saliva used as an adhesive and young chicks. Mites are too small for the adults to see or remove even if they did. Towards the end of the video it appears that the male was viewing the remaining chick as it was swarming with mites,trying to figure out what was occurring. Naked chicks and rodents are fair game for rapidly developing mite populations. Keep in mind why there are bird baths and why adult birds dust themselves on the ground: removal of mites and other ectoparasites.
Those who provide platforms for nesting birds for pleasure or photography should remove the nesting material after the fledge and provide a small amount of similar material on the platform as an incentive for a return.
The world is beautiful as your photography records, but we know it also has many other dimensions that are not pleasant but very real. Now that you know I am hopeful that your (doves) fledge rate greatly increases. Thank you for letting me have a say."
Thanks again to John. Feel free to comment but keep it clean, relevant and professional.
2014 UPDATE: Let me try to reply to some of the comments made. First, I don't know WHY they died. I NEVER interfered with the birds. My best guess is disease. There were literally thousands of mites all over the nest. The lamp had nothing to do with their deaths. Before this, the doves had raised two successful broods. And AFTER, a pair of robins successfully raise four chicks. As for the music... get over it!! I wasn't able to capture much sound so I used music as best I could to capture the mood and emotion of what's happening. Finally, I'm kind of shocked a level of immaturity of people's posts. Come on!! Keep it clean and relevant! One more thing: a LOT of people commented on the birds "stepping" on the young. I've noticed this throughout all of the different birds that have raised young. It doesn't appear to injure the chicks, but I agree it does seem odd. I have many more hours of other bird activities. I just need to find the time to edit them down to the best and most interesting moments.
After raising two successful broods, a pair of mourning doves had their chicks unexpectedly die just days after hatching. I happened to get video the day before and after they hatched. A few days later when I noticed one had died, I set up the video camera to capture the aftermath and how the parents reacted. Truly fascinating view of the natural behavior of how the dove parents handled the situation.
