You are using RC1 of mencoder so you will need to use the other mencoder command. However, from the looks of it, it appears as though your video file may be bad. I never allow uploads of .avi files because .avi isn't a video format. Rather, it's a container format. The video inside of it can be anything. Based on what you are seeing, it's is detecting the video as 1FPS which isn't a video at all and the audio as 8000Hz that is mono, which isn't common for any type of audio (most audio is at least 24Hz). Try a different video and see what happens.