From Chengdu Weishu Technology:
WMV Joiner is an easy-to-use tool for joining several WMV, ASF, and WMA files into a bigger one. Because the program does not recompress the WMV, ASF, or WMA files, the audio and video of the output file do not have any quality loss. And the conversion speed is extremely fast. It also supports to drag and drop files. Only the WMV, ASF, or WMA files, which have same frame rate, frame size, video and audio codec parameters, can be joined. WMV Joiner supports multi-languages, and includes 32-bit and 64-bit versions.