Copy the .hwd file to: ~/.hedgewars/Demos/ in GNU/Linux, Android and Mac OS,
or %USERPROFILE%\Hedgewars\Demos\ in Windows. Restart Hedgewars, go to “Local Game”, then click on the camera button for a list of all your demos. Note: You can only watch demos which are compatible with your Hedgewars version. Incompatible demos won't be shown in the list.