Even though I am a 360 drifter not a PC drifter you asked for my opinion, so I will comment on what I saw and if I get anything wrong due to the PC version being slightly different, please don't flame lol..
Anyway, you are pretty good, what I did notice was you're 'bouncing' the throttle as opposed to smooth throttle work, the lines you took weren't bad, but to get the 'perfect' line you need to be sideways before the turn, and on the opposite side of the road, ie. a left hand turn, get on the right hand side of the tarmac before throwing it sideways roughly 20 yrds before the turn.
Also I noticed you straightened up between corners, to keep a long smooth drift going try to link the corners together, and always look for a good line, and if traffic gets in the way just adjust the drift to go around them as opposed to straightening up and starting again.
PS. with the Z06, make sure it's Stg3 (Stg2 for racing, Stg3 for drifting) and you only need to use 4th gear ;) (unless the PC version doesn't have stupidly short gear ratios like the 360s Z06)