| Stagmeister seems to grossly misunderstand his subject matter. There are several large problems with his claims.
First of all, saying that the truth is a combination of the three theories makes no sense. The Out-of-Africa and multiregional theories are mutually exclusive; either one is correct, or the other, or neither, but not both.
That said, the second problem is the way interbreeding theory is being portrayed here. Stagmeister says that interbreeding theory is true "because humans like to interbreed". Putting aside the logical problems with this statement, note the analogy: "oftentimes the Europeans would interbreed with Native Americans".
What Stagmeister either fails to note or simply does not realize that interbreeding theory relies on the theory that Neanderthals were homo sapiens. Both views are, at best, held by a minority of scientists. Of course, scientific truth is not determined by majority rule, but considering that there is significant evidence based on analysis of mitochondrial DNA that Neanderthals were not simply a different variety of homo sapiens, it's safe to assume they weren't. Different species cannot interbreed; Europeans and Native Americans are both homo sapiens sapiens, so the analogy is incorrect.
The last paragraph is more or less gibberish. Not only does it rely on the fallacious idea that different species can interbreed, but Stagmeister doesn't seem to have a proper understanding of how natural selection works. If a tribe of humans were coming north out of Central Africa, the climate, terrain, ecosystem, etc. would be changing as they traveled. Any of the tribe who could not adapt to those changes would die, leaving behind those who could (obviously). Those who were able to survive the new conditions would be the ones to reproduce, and (assuming the reasons for survival were genetic) their offspring would be much more likely to flourish than the previous generation.
Source: http://www.talkorigins.org/faqs/homs/mtDNA.html | 
