If some videos are working and some not, then it is server’s issue or the XVideo’s causing it. Xvideos is constantly updating their site so that is why some videos work, then stop working and then work again. The plugin needs update anyways.
There is nothing we can do about that since it is the issue on the XVideos’ side. They still give the content from the http connection but they will change it to https, it is only a matter of time.