Seems this is another add-on which will not provide further support for Pale Moon - as written in the http://www.downthemall.net/main/install-it/downthemall-3-0-beta-6/ beta blogpost:Moonchild wrote:If you want to take the change up with the DtA developer they can probably make sure their new version STAYS compatible, if they want to provide support, anyway.
"Old Firefox versions, such as Firefox 3.6 and ESR are NOT supported. Forcefully installing the add-on will NOT work, because of missing features in these ancient Firefox versions. Pale Moon is not supported because it is still using an old version code base."
So, it seems most likely a fork would be necessary if further support is wished. if i consider that Previous betas worked - have used them also for some time, while Beta 6 - even when forcefully installed is totally broken in Pale Moon. Guess they have decided to go Australis only now.