The newest release of VirtualDub, 1.6.1, has support for the Athlon64. That is to say that there is a separate 64-bit version available for download. Interesting.

"The new version, v1.6.1, adds a support for AMD 's AMD64 processor , but the 64-bit version is released as a separate download from the usual 32-bit distribution package. Anyway, the popular open source video editor once again has a rather impressive and long changelog since the previous 'experimental' version, v1.6.0."