how to download and install programs from sourceforge

I don't have time to check out xvidcap and write a walktrough specific to that package, but I guess this generic explanation I wrote a while ago could be helpful.

You need to download "Source .gz" package (xvidcap-1.1.4p1.tar.gz), open terminal and cd to folder where it is downloaded (on my system it's MyDownloads:

$ cd ~/MyDownloads/

Then decompress it and cd to newly created directory:

$ tar xzvf xvidcap-1.1.4p1.tar.gz
$ cd xvidcap-1.1.4p1/

Now you configure it:

$ ./configure

If configure script says that you're missing some libraries, you need to install them (you'll probably need -dev packages, eg libglade2-dev if it says you don't have libglade-2.0) and re-run configure. Use your package manager to find and install these.

Now you would normally type make to build it, but in this case configure also builds the package, so you only need to install it after it builds. Become superuser and install it:

$ su
[type root password]
# make install
# exit      (to stop being superuser)

Run it and have fun:

$ xvidcap

If you decide that you wish to uninstall it later, you need to do this (in the same directory you did make install in):

$ su
[type root password]
# make uninstall
# exit      (to stop being superuser)

You may also uninstall libraries you installed when configuring it, as you don't need them anymore. Use your package manager to uninstall these.

If you're using Ubuntu (or an Ubuntu derivative), you should use

sudo make install

instead of

su
make install
exit

.

Similar for uninstall.

also, make uninstall is not always supported well - many programs actually skip that option ­

... as you could have read in the initial reply

One way to replace make uninstall might be usage of checkinstall instead of make install to create a RPM- or DEB-package and then installing this through package-management. In case the package has to be removed later this can also be easily done through package-management.
I usually use this when I just want to test a program and I'm not sure if I'll keep it.

A semi-off-topic note:

When using 'su', you should almost always use 'su -', which will import the root user's environment variables, etc.

Well, in this particular case it is supported.