When you produce an AVI video using a codec, that codec must be installed on the computer where you view the videos. Much like viewing a PowerPoint file requires that PowerPoint be installed.
Although Camtasia Studio can produce AVI videos using any standard Windows codec, by default it uses the TechSmith TSC2 codec.
Camtasia Studio can use other codecs installed with the standard installation of Windows such as Microsoft Video 1 or RLE, however TSC2 will generally produce smaller files.
You can convert existing TSC2 AVI videos to use a different codec by placing the AVI on the timeline in Camtasia Studio. Click Produce and share, select Custom Production Settings, choose the AVI format and then click the Video compression button to choose a different codec.
Workaround: Distribute the TSC2 codec
You can download and install the TSC2 codec from here.