The amount they jump is significantly less for the yellow belt compared to the blue belts.
EDIT: Look at my reply after this or go directly to the new video instead at https://drive.google.com/open?id=1vOeD0 ... ck4jTB6hgq
1. Have some flow of items on a 4 wide same speed parallel belt bus that isn't being significantly being filled (like 10% density or less)
2. replace one of the belt tiles with a different speed belt
3. the very moment that you replace it all items on belt tiles near that belt for the couple seconds will get that jump when they enter an area around it (approximately 3 to 5 tile radius I think)
Seems to happen all the time for that situation in the video and save file, though I haven't done any testing yet in other locations.
EDIT: The google drive folder link is now in the follow up reply below
The forums just said "Sorry, the board attachment quota has been reached." when I tried to upload the save . I will have to do that tomorrow then.