LOL, greenfig, you just asked what is BG was... so what is BN?
I agree that sealing is not necessary. Nor is even washing or disinfecting (though many people choose to do this). I've started great numbers of figs the past few years without doing either (last year two prized figs were given to me, both sealed..and both rooted). The most important factor IMO is keeping things only slightly damp, and using cuttings as fresh as possible.
I was kindly given 3 cuttings each of Black Madeira and UCD Black Ischia a couple months ago - the only cuttings I've rooted this season. They were extremely fresh and healthy. I cut them in half, and got all 6 of the BI to root, and thus far, 4 of the slower BM's to show roots. They are now all fully acclimated to the sun, (and took their first real rain today) but still in their starting bags (with many holes punched in them from the beginning). I'm happy as a clam. :)