You clip the bottom corners, then seal the top around the Fig stem. It works.

Does it get too humid in the bag and problem with mold developing? 

Nope,the air comes in from the openings you cut at the bottom.

Very economical, I use pantyhose on my rare figs. It keeps the birds off and the bugs, but when it rains I remove them. I just ordered 100 Organza Bags off ebay and hopefully they will work as good if not better and I won't have to hand sew another drawstring on a piece of nylon pantyhose ever again. I'll post my results and tell you what size bags work the best if they work at all. for 100 bags I paid around $8 including shipping. I like your idea and it might work in philly but in SC those figs would be stewed in the bag even with the holes for ventilation.  

I wonder if anyone has tried the tyvek envelopes you can get as priority mail from the postal service?  Free and they breath, are white.  Seems they would work.

You can't see the figs in tyvek.  I've tried a few organza sizes and I like the 5x7 the best.  Smaller ones are big enough but a little hard to put on.  Especially if you have thinner fingers YMMV.

I have never had problems since I have been using white organza bags.

I did not find zip top bags to be effective. I tried them in Houston in 2007 (maybe 08). I had placed several over figs when I had found some damage to others. In the morning only one had survived. Some of the bags were laying on the ground and empty, and others were dangling from what was left of the fig. I have pictures somewhere, but can't find them.

The one that did survive had been damaged by the humidity by the time it ripened.

 MvsB with pantyhose   Tim Clymer Enola Italian #1 with organza bag

with pantyhouse it's by feel at leaste with organza bags you can see inside

The organza bags may work agains birds but useless against my rats and squirrels.

get a outside dog or cat it helps