After Effects error ; could not allocate sound memory

M4V is a heavily compressed option, it might be worth comverting it to a WAV file and trying again.

Impossible to say much without any info about your system, audio preferences, audio contained in the file and so on. The first thing to check would be whether AE is even able to read it at all and generate a waveform for it. Otherwise it may simply need to be transcoded to a "real" MP4 as it appears to be some odd file directly from a camera. It may simply contain errors or the audio be multiplexed in a weird way in the streams.

Mylenium