1. Extract the contents of the zip to a folder.
2. Launch PowerPoint.
3. Click on Tools | Add-ins to bring up the add-ins window.
4. Click on Add to bring up the 'Add New PowerPoint Add-in' dialog box.
5. Navigate to the folder where the contents of the zip file was extracted and select 'capture.ppa' and click on OK.
6. You might be prompted with the macro virus warning. Enable the macros. When the Add-in is properly loaded, it will display a 'X' against the add-in name.
7. That's it. You have successfully loaded the add-in. Now put it to use.

Note: If you are unable to load the add-in check your macro security setting.

Click on Tools| Capture Show...

Select appropriate capture mode and output type from the dialog seen below and click on 'Begin'.

Note: In Semi-automatic and Manual mode of capture any pen annotation can be captured by performing a right-click on the slide and selecting the 'Capture This Screen' option.