that second one is what i was taught as double clutching. You dont need the clutch for it though, you bring the rpm's up in gear and let off the gas a lil' and pull it out of gear, allow the rpm's to drop to a compensating rpm depending on the type of tranny and engine you have, and itll slide back into gear. Such as on my focus its at 3500 to 4000 to pull out and 1500 to 1800 to slide back in. Downshifting is in the reverse. 1500 out, 3500 in. It can still be used in cars today. It'll screw up synchronizrs though if you miss though, not good. You better know what your doing when you do it.