Try to use a recorder, im using a pretty one - PCHand Screen Recorder.
it could record any activities on the screen and the audio whatever u hear, even the left and right mouse clicks and mouse highlights can be recorded to be displayed in your recordings. i think it is the perfect assistant to make videos for u.
I tried a lot before bought, it's easier to use. It also provides a free trial version. U could try it.
hope it could help u.
http://www.screen-capture-record.com/screen-recorder.html