See/edit local storage settings.
Open the [1] folder listed as "local environment" from the tabs at the bottom.
Once you successfully open the local storage, [2] use the slider to set "res.nimg.jp (or www.nicovideo.jp) data saved to computer to "unrestricted". If [3] Do not show this again is checked then the slider will be disabled.
Click "Proceed To Check Player Display"
Check your browser and close all unnecessary browser windows (except the two below)
to make sure Adobe Flash Player settings are saved properly.
●The window (or tab) displaying this help information
●The window (or tab) being used to change your settings
Once you have completed the above click the "Website Local Settings." (see below)