You will not get information regarding Non-O extensions from an Embassy website. The information is obtained from the local Immigration Office where the extension application will be made as requirements can differ.
I got mine in Sa Kaeo province in 75 minutes for 205B. I got my resedence certificate from Immigration (free, took about 25 minutes) then found a clinic to get the medical certificate for 100B (blood pressure tested and a few questions for the tick boxes on the pro forma). Out in about 10 minures. Took these plus my UK licence, IDP and passport (with Non-O Visa) to the DLT the next working day, registered, did the 3 tests (braking/reaction, colour-blindness and depth perception) and that was it, no test, no video, nothing else. Easy and legal, valid for 2 years then renew for 6 years.