Following Script join multiple videos

VirtualDub.Open("movie_1.avi");
VirtualDub.Append("movie_2.avi");
VirtualDub.Append("movie_3.avi");
VirtualDub.Append("movie_4.avi");
VirtualDub.Append("movie_5.avi");
VirtualDub.Append("movie_6.avi");
VirtualDub.Append("movie_7.avi");
VirtualDub.Append("movie_8.avi");
VirtualDub.Append("movie_9.avi");
VirtualDub.SaveAVI("out.avi");
VirtualDub.Close();

Save the file in folder where videos are present.

To run the script, Run VirtualDub. Click Files > Run Script, now select the script. Now all the video files listed in the file will be joined and resulted file saved as out.avi.