Since a moment no recording in Youtube is possible. Despite the removal of the add-in from Firefox, uninstalling the ANTDM software according to the description of the support, then reboot and new installation with rebooting again and then renewal of the add-on in Firefox, the small ribbon, which previously came up over the video to start a recording, no longer appears - even if the recording functionality in the settings of AntDM actually displays a functionality with green.
Other videos that are not linked to YouTube can still be recorded. Obviously, YouTube wants to successfully prevent the recordings with AntDM (also with other downloaders, e.g. at Youtube Downloaders, who issues an error message, just the same thing is happening), what arises to me, for which I then paid the amount for the PRO version of AntDM...