Install Autohotkey from here and save following script as tmp.ahk and execute the file by clicking.
You can rewind Youtube videos for 1 second by z and forward Youtube videos for 1 second by x.
WinActive("ahk_exe chrome.exe"): The feature will be only enabled on chrome.exe
WinActive(" - YouTube"): The feature will be only enabled if the window title of the current chrome tab matches to regex - YouTube