This is batch number 6 out of 8 batches raised this way over the years. NO heat lamp, in full view of the rest of the flock, temps often in the 20s dipping into the teens. Integration with the rest of flock started at 3 weeks using those little doors that are visible in the video, full integration with the flock at 4 weeks, brooder and all heat removed at the end of that 4 weeks, with the brooder pen torn completely down. No dust in the house, no cheeping all night long. Strong, confident chicks who have learned how to be chickens from watching the experts. Stress levels on me and on the chicks cut in half, they self-regulate what they need for heat instead of me, a chart and a thermometer forcing it on them.
I'm not saying this is the ONLY way to raise chicks. I don't have that right any more than anyone else does. This is totally unconventional, and I get that. I also know that everyone has to do what's best in their situation, for their setup, and what's within their comfort zones. And however they are raised, they do indeed need a secure enclosure.
But this is how I, and many others, are raising them - by duplicating a broody hen as closely as possible. If a 2 pound hen can do it with no experts, books or assistance, then why do we do it so differently and think we're doing it better?