This video is kinda related to this topic.
The guy at 2:27, though. His explanation of the OK had me crying with laughter, but nice observation there. Somalis usually make that gesture when they are describing something with precision, it's a freaking diirad.

Also died at the guy who said dilaals(brokers) use the okay and the salaaxid gestures a lot.
Here's my take:
Okay sign= See above. Can also mean "cay", as many already mentioned.
Peace sign= 2, us two, twins, comparing two things(is barbar dhigid).