after some fiddling, i managed to make the videos work. i followed the virtual dub guide posted in the forum, except that i changed the resolution to 224x176. for ASF, WMV and videocd formats, i used the virtualdub-mpeg version also posted on this site. after converting to avi, i then used AVConverter that came with the unit. I can see no difference between the High Quality and Normal Quality settings, except that the High Quality results in a bigger file. As an end result, i chose Normal Quality and it plays perfectly on my rockchip mp4 player. Hope that helps.
I am still reseatching about ID3 tags....