Capturing screen and oneself at the same time

Hi I create small web seminars for my students. I would like to capture my computer screen and also myself while I give the explanations (like MacMost).

I have been doing in the past with Quicktimes for the screen capture and "3rd eye mirror" so my webcam video appears simultaneously on screen.

Unfortunately "3rd eye mirror" does not work anymore as I get the following error message : "The movie contains an invalid data reference". Here are my questions:

1) can anybody help me solve problem the error message refers to?

2) can you suggest another mirroring program that show the content of the webcam, but it needs to always stay on top

3) any other suggestion to record a video with oneself and the screen at the same time.

Thanks

thanks guys, I have looked into both of them, screenflow is a bit expensive but seems very professional, I wonder if the learning curve is steep... I will try the trial software... thanks again