I have seen people using a number of tools to create screen captures of thier cool application for demos, blogs posting on video sites etc...
I have been using this tool for a long time, but it's existense is unknown to many. So here are the details
Windows Media Encoder
Home Page : http://www.microsoft.com/windows/windowsmedia/forpros/encoder/default.mspx
Download Page : http://www.microsoft.com/downloads/details.aspx?FamilyID=5691ba02-e496-465a-bba9-b2f1182cdf24&DisplayLang=en
How much does it cost?
It's FREE !!!
Glimpse of the options in the wizard 1st page (loads of options more...)
Is this tool only for screen capturing?
No way, go ahead and explore yourself
The output file is either WMA or WMV, and you can also select target profile like desktop, pocket pc etc...
Go ahead and showcase your applications & mashups live on those video sites :)