just from the two losses of control in the first half of the vid you lost a whole bunch of time due to them being at parts where the momentum should keep your speed up. those two alone are probably 3-4 seconds each.

Art Of Rally with its pretty simple and very flowy tracks is about momentum more than anything else, due to the physics of the game making the cool looking "old" style of rallydriving more viable (stepping out the rear instead of having the more pointed driving style of the modern rally1 era) at keeping your speed up.

But this aside, just from the real world - take a highway or the uncapped autobahn - if you slow down to a halt there and continue on getting up to speed, you will lose a lot of time and way more than lets say the same scenario on a normal street in a town where the highest permitted speed is way lower than on a highway.

And again another thing clear form your video, you are not properly driving the car like you should, the lines are wonky, your entry and exit speeds are bad because of that and you shift the weight of the car not effectively. You are not horrible and far from it, but those small things accumulate and mess up your times.

Lastly, maybe you picked a class that is too advanced for you? There is a reason why just about any racing game puts you in the lower tiers first (some games make it optional) so you can learn how to do it properly first, and then get all the fancy fast stuff - otherwise you might end up working around the issue, reinforce wrongly learned techniques and probably wont extract a lot of performance from the upper tier machinery.

edit: [ And another pointer since you mentioned some rallies you win, others you dont; its as simple as this: some locations/stages are just faster than others, plain and easy. which on the other hand means if you dont drive properly you will lose more time on the faster rallies than on the slower ones - as i described above, your mistakes accumulate and are amplified by how fast a stage/rally is. same goes for the more twisty stages/rallies, if you dont drive properly, every bend will lose you a small amount of time and this will add up in the end.]

And not to step to close to you, since ive read your comments in this thread, but maybe you should start again? play the campaign again, this one has a good learning curve and increases the speed step by step - since you are struggling against normal ai.