Hi aeiouer,
What are you using to convert to .AMV videos?
Also what version?
What settings are you using?
There is also a freeware AMV Converter called "MPX Converter" created by a member on this site. Have a look here:
MPxConverter. It can be downloaded from this site under the [Downloads] --> [Tools] section on the left hand side menu bar. Try that and see if that makes a difference.