Files play perfectly on my PowerMac, picture and sound ok.
The files are burned "as is" and not converted to DVD format.
I used to find that some AVI's played soundless in Quicktime, these in particular I would convert with VisualHub and burn to dvd.
Toast is used to burn the discs. The present disc was burned at Max possible and then 16x but both have presented the problem of heavy pixellation with garish colours, although sound was aok.
Media is a mix of: Infiniti, Fuji, Prodisc and Verbatim (all inkjet printable).