yeah its free GNU license is just that. Open source and free - however you can donate if you like, which is a good idea if you use it all the time, only fair.
a) off-topic
b) if you'd just downloaded it, you would have found out
c) virtualdub is great, especially 1.3c which still has asf/wmv support (although the program lacked a lot of features back then)
Depends on what you want to do. Primarily I use it, or used it, to convert between encoded types rather than editing directly, as it can be rather limited.
if you need to record sound maybe you'd better use Audacity (http://audacity.sf.net) wich is open source too.
Virtualdub as also nandub are use for video encoding/conversion or even for cam recording, nandub especially is also very suitable for lossless videocutting/merging they have also some basic filters to apply to the video streams.
the best open source video editor out there (jakarta might be an interesting project, but vdub is so much more mature). as mentioned, 1.3c can open asf, but the latest versions are amazing at capture and managing sync issues. highly recommended.