I am having the same problem on Chrome. I had problems uploading video if I just click on the upload square to call the file window but if I drag the video into the square on the upload page it works fine.

But then the upload snap issues arises. I tried taking a snap directly from the video and that worked in that it took the snap and saved it to my computer. But it will not upload it properly. I renamed the image from "snap" to a more descriptive title and it still didn't work.