VirtualDub is described as 'Video capture/processing utility for 32-bit and 64-bit Windows platforms (98/ME/NT4/2000/XP/Vista/7), licensed under the GNU General Public License (GPL). It lacks the editing power of a general-purpose editor such as Adobe Premiere, but is streamlined for fast' and is a very popular Video Editor in the video & movies category. There are more than 100 alternatives to VirtualDub for a variety of platforms, including Windows, Mac, iPhone, Web-based and Linux apps. The best VirtualDub alternative is Kdenlive, which is both free and Open Source. Other great apps like VirtualDub are Shotcut, Avidemux, DaVinci Resolve and OpenShot.
It is the best alternative to virtualdub (that is discontinued) because an evolution with many improvements. It is actually silly that it is not at the top of the list.