As shown in the video, it looks like the print head stops when printing small infill lines. It doesn’t actually stop, but I think it appears that way because it’s printing so many tiny line segments. This causes over-extrusion in the area that the print head is slowing down. Adjusting the “Quality > Precision > Resolution” setting reduces this affect - ie changing from 0.012mm to 0.12mm reduces the problem. However reducing the resolution has the negative affect of not printing circular walls and small features well. Interestingly the part on the right in the video slows down more than the part on the left even though they are clones of each other.
Not sure what that is, you may need to supply more data, but one bizarre thing I recently found out about is the quality of the SD card can cause strange pauses.
Make sure you’re using a good brand Class 10 SD card. It could be pausing while waiting for a Write cycle, especially if you enabled Auto Recovery of Step Loss (in Print Options on the screen).
Not something that would occur to you right off the top, eh?