Ok whats up with certain videos not being played on my WM Device

[Freshumz]

Ive used WMP and TCPMP.72 RCO (not sure if thats the name), but for some reason it is still selective over the videos it plays. I managed to get a video 183 mb working fine but other videos in its range wont, while some play sounds with no video. Why is that? is there a limit to the video's quality or size?

Thanks in advance :p

[Rudegar]

what videos can be played on any device always comes down to if the program have access to a codec http://en.wikipedia.org/wiki/Codec
what codec is being used can often be directly related to ext of the file
of the media im question
apart from avi which can be many various codecs