An alternative method would be to open VirtualDub, File > Job control [F4] > Edit > Process Directory
This works pretty good on a folder full of .avs scripts. But be careful with .avi files... since VirtualDub outputs into the .avi container, if you do not choose a different target directory than your source directory, you'll get an error or possibly even risk overwriting your original source files.
Once all jobs are queued up, you should be able to see them on the list, and click Start.
(And, as always, be sure to set your Audio/Video compression settings beforehand too; otherwise you'll be exporting gigantic Uncompressed files that won't be in the format you want, which will eat up even more space on your hard drive than lossless files)