I know this was already suggested by another user but I would just like to extend upon the idea. I have made a workaround for this effect which uses multiple layers of different opacities, where each layer is slightly ahead of the previous by 1 frame.
This is what it looked like in the timeline:
This is the result of this workaround:
https://bit.ly/2XLjIGH (Mediafire download directly from me)
This is the MLT file so you can try this effect yourself with your own videos:
https://bit.ly/2XNc2DF (Mediafire download directly from me)
This method could probably be compacted into a neat filter where perhaps each track could be spaced 0.5 frames apart instead of the 1 I used here. A slider to adjust the amount of blur would also be useful.
I hope this idea is considered.