Hi Mark
I'm using TinyMCE as the editor.
On original install it reported that the mambot was installed correctly and, since your post I have uninstalled it and reinstalled it again whereby I get the same notification.
However, the mambot is listed in the site mambot's list as 'AllVideos Plugin' (same on both install occasions).
I am on "Joomla! 1.0.12 Stable [ Sunfire ] 25 December 2006", on a cancer charities site which I have 'inherited' the responsibility for (i.e. you know about computers, we have been left in the lurch can you help out... Hence my newbie status!!).