1) ffserver don't not work. 

ffmpeg development are now concentrated on the codec and format
handling. New developments broke ffserver, so don't expect it to work
correctly. It is planned to fix it ASAP.

2) I cannot read this AVI file.

Even if ffmpeg can read the AVI format, it does not support all its
codecs. Please consult the supported codec list on the ffmpeg project
page.

3) I cannot read this Real Audio/Video file.

See (2). ffmpeg only supports Real Video 1.0 and AC3 as Real
codecs. It mean that you cannot view files encoding with real tools
after version 5.0.

4) I get audio/video synchro problems when grabbing.

Currently, the grabbing stuff does not handle synchronisation
correctly. You are free to correct it. It is planned to fix it ASAP.