It looks like you have short/quick steps on steps 2-3-4.  When you're on your 4th step you can see your momentum shift to the right as you're loaded up going into 5.  At about the 6 second mark you can see it, so you're drift is towards the end.  It looks like your swing is late/behind that drift may be compensating for it.

That's just what I'm seeing.  Someone else may be able to articulate it in a different manner.

ADDED NOTE:  If you really watch step 4 go into 5, you really get the slide leg going very far right into the slide.  I could see that being an issue when you're moving way in (5th arrowish) and swinging the ball.  I'm not sure how you work it when going more coast-to-coast.

That's just my impression, others (more qualified) should chime in.  Basically, what it looks like you're asking is to identify where your drift is.

What stood out to me is that after your first step, 2-3-4 are very quick, that lead into  a long step 5 (slide step).  Watch the location of your left foot from step 3 to step 5.  There's your drift.  After the ball is released

Generally, you're not walking to the line in an effortless manner and in a straight manner.  If you're repeating shots then I wouldn't change anything but I'm not sure how you move in and swing it.  With a smallish step 1 and quick steps 2-3-4 it seems like the swing would naturally have to catch up.  It has to create a timing issue.

Interesting ball return there too.   

You're a product of your environment. Above ground ball returns. You have body positions of a guy that wants to hook it in the first half of your approach and then don't clear your hips or trail leg because if you did you would kick the ball return. Thus the drift in your last step so you don't fall on your face and then falling off the shot.

Define clearing hips and trail leg please

Getting your ass out of the way so you don't have to swing around it and can have some leverage.

lilpossum:

Some good suggestions being posted here. There are many reasons for "right drift".
After reviewing your video, what really stood out for me was the relationship between your starting position and your target out on the lane. Your left foot in your stance is positioned around the 24th board on the approach. Your lane target looks to be close to the 10th board. This represents a spread of 14 boards (between your left foot in the stance and your target: 24-10=14 boards). This represents quite a gap between your left (slide) foot and your target. So, as you go through your approach and you are closing in on the foul line, your target (10 board) starts to appear more farther to the right of your line of sight.
This gap is not as noticeable from the back of the approach in your stance but it becomes apparent as your body approaches the foul line. As you enter the final phase of your approach, your instincts tell you that you need to close this 14 board gap in a hurry, so, on the last step, you readjust by stepping to the right, thereby closing this big gap. You close it quite well I might add, as the ball ends up very close to your left ankle at release ( a good thing). Some folks do the opposite at release.
They step to the left. For power players, they instinctively do this in order for their
bowling arm and hand to clear their right hip and to allow them to project the ball from left-to -right. This is fine AS LONG AS their bowling hand "follows" their body
to the left and closes the gap between their sliding foot and their lane target at release. If their bowling arm fails to follow their body , they end up committing
the "sin" known as "stepping out of the shot". This will cause the dreaded chickenwing
as the bowler now tries to hit a target that is too distant from their sliding ankle.

You are doing precisely the opposite. You are "stepping in" to the shot on your last step. Many traditional strokers do this to varying degrees. Too much right drift will
force a bowler to realign their downswing to such an extent that it will often result
in the ball being "topped" with the fingers. This will cause a weak release.  Your drift
is approximately 8-9 boards to the right--- somewhat excessive. One way to correct
it is to begin your stance farther to the right from where you are now. If your target is
the 10 board, you will want to place the inside edge of your left shoe on around the 17th board (you are on the 24th board currently). You will now want to concentrate on walking as straight as possible to the foul line.  If you do, there will no longer be a need to suddenly fill that large gap on your last step.  A normal slide foot-to target
spacing is approximately 6-7 boards.

Correcting drift takes time and patience. One popular method to utilize is the "tightrope" method. This is where you visualize that you are taking your entire approach as if you were literally walking on a tightrope. 

Best of luck to you!

I suggest having a cross over step. I think what they mean by move your ass out the way is the cross over step. First step is your timing then second step crosses over your first thus your kinda drifting left but when you finish you slide toward your target so I think your technically going straight .

Here a video that help me https://youtu.be/VpP9c36ogiQ

Take my advice if ya want I'm no pro haha just suggestions