AVI format Codec not supported

Hi folks,
Hello and thank you in advance for your help! =)
So here, I have a TV Thomson LCD to which I can connect a USB key to play movies for example. My problem:
I have two movies on my USB key, the second in AVI format (supported by the TV), which can read without a problem, but not the other and it gives me a message:
"Codec not supported" (meaning the sound of the film but there is no image).
How do I play this movie?
