watch.exe is a process by Mustek, which allows you to scan by clicking on a system tray icon. "This program is a non-essential system process, but should not be terminated unless suspected to be causing problems. "
Note: Also related Eicon communications software
Non-system processes like watch.exe originate from software you installed on your system. Since most applications store data in your system's registry, it is likely that your registry has suffered fragmentation and accumulated invalid entries which can affect your PC's performance. It is recommended that you check your registry to identify slowdown issues