Actually, if you read the fine print, you realize that the advertisements say something like Bi-Monthly, but the fine print says bi-weekly.
Bi-Monthly: 2 payments exactly everything month.
Bi-Weekly: 1 payment every two weeks.
The two aren't equal.
There's a difference between bi-monthly mortgage versus bi-weekly mortgage. Bi-monthly doesn't save you jack on the mortgage. Bi-weekly, means your making extra payments . You get the same effect roughly by making 1 extra mortgage payment applied completely to principle each year, spread out over 12 months.
Been, there investigated that. At least BofA are pretty upfront and honest about it if you ask. If my wife and I could have skinned a mortgage another way, we would have already done it.
I just wonder if I get the principle down to really low say in 5 years, could I restructure remaining balance over the remaining term of the 30year loan at the same interest rate. I doubt it, but haven't tried asking.