what if any standard definition can be played on the Zidoo, i have tried some Avi and some MKV with no luck Zidoo on screen message cannot play video
It could be re-encoded with appropriate software - Staxrip is my favourite but I think equally as good is Handbrake. I would hazard a guess that they are divx files.
Often DIVX files can be played by just changing the header info saying they are XVID files. https://www.tweaking4all.com/home-theatre/fourcc-changer/ Set it to change the DIVX header into a XVID header and all done. Available for MAC, Windows and Linux OS versions. Bulk conversions are supported. An easy try.