The formerly used Flash player technology is totally disappearing in modern browsers, thus making the previous interfaces incompatible*. This change of technology answers the community’s demands and allows modern and innovative functionalities. Check that your browser is updated. Close the background third applications as well as your browser’s inactive thumbnails.
* We are aware that some of you do not have a configuration which allows to play and are sorry about this, but we cannot, given the disappearance of Flash, do otherwise: Adobe Flash just took another step towards death, thanks to Google
** These configurations are given as examples, the reality is even more complex so your config may appear , - without actually being - compatible.