The problem is: Dingoo only plays flash 6 files. So newest animations like the ones on Newgrounds are not likely to work.
To check the version of your .swf, open it with an hexa editor and look at the 8th byte.
43 57 53 06 // flash 6 version
I got some old flash files from albinoblacksheep website, but basically you have to dig the oldest files you can get and check the version with the hexa editor
hope this helps