Can the N-Gage play WMV/AVI/MPG/DAT/MPEG4/VCD/DVD video files?
No – you need third party software to play most video types. SmartMovie is one example for XviD AVI files and it offers full screen landscape viewing too. For the rest, I have not heard of any players as the bitrate for the other videos can be quite high. The only ones that you can play without additional software are 3GP and RealMedia(RM) files, both of which separate encoders are required.