Even without the double load (edit it out) she would still be slotting and shifting.
edit: or how many also look at it, she would still be shifting and then swinging.
Don't forget the 'dropping barrel/bat and level swing'.
You can edit out that double load with the right software.
I just went back and checked several other videos from Tuesday and she is more or less doing the double tap in all of them. A few weeks ago she was struggling a bit with the timing of the load. She was stepping while she was starting the swing. Coach had her start doing the stride/load early, like as soon as the pitcher starts her windup. Then hold the load position and swing when appropriate. That is the first step you see in the video. It looks like she is falling back on the old bad habit of stepping and starting her swing at the same time which is the second step. It is not as noticeable in this video, but in a couple of the other ones the hands/arms are moving forward before the front foot has even touched down. Coach has been teaching her that the front heel coming down should be the trigger of when the hands start moving. I think this double step is contributing to her getting her body moving forward and getting too much weight transfer to the front leg. I'll talk to her coach about it next week. I think we either need to stay with the early stride/load, but have her make it a bit more deliberate and reach a little further forward with the left leg so she feels it or not do the early stride/load and try something else to have her not stride and swing at the same time. Does that sound right?
If she stays with the early stride then your doing a no stride, she can't be taken a second stride while trying to initiate the swing at the same time. Work on the no stride swing.