Maybe u can try ImTOO Audio Maker (
http://www.imtoo.com/audio-maker.html). After u install and start the program, u can see three main functions,that is Convert, Rip, Burn.
Click Convert module, then click Add button, import the video files from which u want to get audio into the file list, and check all the items in the list, then select the needed audio format in the Profile area, finally, u just need to click Convert button, audios of these videos will be converted to the selected format and output to the selected folder(default to c:temp). moreover, u can click Advanced button in the Profile area, enter advanced setting to set some advanced parameters.