I never used Camtasia Studio 8 but here is a tutorial on how to do that stuff I found for you
About Video Effects
Add video effects to Camtasia recordings, video clips, shapes, and text to enhance your video. Video effects include:
Transitions: Transitions apply to the beginning or end of media on the timeline.
Filters: Filters apply to the entire duration of the media on the timeline.
Actions: Actions apply to media over an interval of time.
Click a filter button at the top of the Video Effects pane to display all effects or one type of effect. For example, click the Actions filter button to view only actions. Click the All button to view all available effects.
Video Effects Filter buttons
Preview Video Effects
Hover your cursor over the left-side of an effect to preview the video effect.
Hover cursor to preview effect
Each effect displays a preview of how the effect will appear when dragged onto the timeline.
Preview effect display on timeline
Add a Video Effect
Click the Video Effects tab Video Effects tab.
Drag the desired effect from the pane onto the timeline or canvas. As you drag the effect, Camtasia adds a yellow border around the locations you can apply the effect to.
Apply effect to yellow highlighted areas
You can only add and edit video effects while in the Video Effects view. If you click the Media & Library tab or the Audio Effects tab, the video actions shrink on the timeline.
Action collapse on timeline when switching views