It is probably a flash problem. In your home folder you will find flash stored
in the .mozilla/plugins folder (it is a hidden folder so won't show unless you
have hidden files displayed). I am assuming that you have flash installed since
it works with one browser, but not the other. Copy the following files or drag
and drop them if you are using KDE (do not move them, you want them in each
place) to the plugins folder of Iceape. The files are called: flashplayer.xpt
and libflashplayer.so. You need both files in the plugins folder for all of your
browsers.

I do not have Iceape installed so don't know the Icepae folder name. It is
probably called .iceape/plugins. Iceape is not an official Mozilla product so it
is not likely to share Mozilla's plugins. It is also hidden. But Seamonley is a
Mozilla product so it will share the plugins.