It means the video format can not be played. This may be because you do not have a full featured xanim installed, see the next answer for more details.
There are some codecs that will not be playable for the foreseeable future, the one that may affect you the most is Sorenson as used in QuickTime 4.
Go to the xanim home page and follow the instructions to install the cinepak, indeo and creative video codecs. You may need to recompile xanim, but check your distributions documentation as some are easier to install than others.
There are two ways to check, which you use depends on how you installed AKtion.
Check the output of ./configure, you should see "checking for VidMode extensions...". If the script prints a "no" after this line, then you don't have the extensions.
Look in your system for two files called: libXxf86vm.a and libXxf86dga.a, if you have them, good.
In both cases, if you don't have the extensions, check that you've installed the XFree86-devel rpm package from your Linux box. The extensions are included in this package.
Try switching video modes with CTRL-ALT-numpad +, if nothing happens you may just have to enable additional resolutions, see the next answer for more details.
You should have a video configuration utility provided with your distribution. If not there is always XF86Config available.
Enable as many resolution modes as you can, at the very least you will want to enable 640x400 alongside your standard everyday resolution.