I made a WSO video in .WMV but it occurred to me that many people can't play .WMV because they're on a Mac. So then I converted the video to .MP4 with Any Video Converter and now the sound is all echo-y. The sound is definitely not echoing in the .WMV version so it seems like I must have done something wrong during the conversion. Does anyone know what could cause that problem? Should I convert the video to yet another format?