The video shows some locking side widows (you need doors). Available at (least they were) on ebay. This are the best fitting I have found.
Ebay link (German) Ebay Item.
It depends on the use. I will be using my Twizy all through the winter like I did on the Motorbike. For me the windows in winter would help.
If you do not have doors on yours, you may not have seen how these windows are fitted. The inside door card has 3 large screws/ bolts just below the top edge. These are unscrewed and the window dropped into place before refitting the screws. This means it is not a big job to fit or remove the windows.
Today while I was out the rear seat got very wet, not the driver though, as I don’t usually have a passenger I would not fit the windows until late on in the year and remove them March time. A bit like when I used to fit the inner to my motorbike coat and trousers.
I didn’t like the ‘sail’ type windows on the Twizy as it makes it too slow to get in and out. Therefore it has to be a ridged window. The ones in the video are the best fitting. there are others that leave a hole at the front to get your hand in to open the door and for ventilation and do not curve down round the back of the door. finestrinirenaulttwizy (Italy)
We will all have different needs and these appeared to be the best of the current ones. By the time I want some there may well be others.
Let us know how you solve the problem if it is a problem in the winter.