How do you create jpg format video's?

Question

I've always thought .jpg was non-animated, but I've recently found several animations in .jpg format.

1) The obvious question - how do you create .jpg video's directly in the fileformat (not using javascript, for example)?

2) It's both hard to find examples of more .jpg format video's (unlike gif's, there aren't exactly archives of animated jpg's), so if you've found any notable .jpg video's not listed below, please also post them below!

Answer 1

These are no jpgs. They are gif files just named jpg. You could see the file details to see they are gif. There are no animated jpgs.