Try saving the project. Closing Camtasia and reopening the project.
Camtasia 8 is a 32bit program.It cannot access a lot of RAM memory. So the longer you edit a project.Or after you've applied a lot of edits. Whichever comes first. RAM memory becomes saturated and the editor slows down and can become glitchy.
Saving your project and restarting Camtasia clears out most of that memory.Giving you a fresh start so to speak.
One precaution, the program no longer retains your previous actions in the project.So the ability to Undue previous actions are lost. Other than that, you can continue to edit and change anything you want. I just thought I would mention it.
The container format is a definition of how the file metadata and data are structured, excluding how the video is actually encoded (which the codec determines). The container file holds the metadata and compressed video data which is encoded using the codec. The container format is also more generally called “the format”, and is reflected in the file’s extension. Common container formats include .AVI, .MP4, and .MOV. Container formats can be paired with different codecs that influence what devices and programs the file will be compatible with.
In short, not all videos are made alike.
Converting a video from mp4 to mp4 using a video converter. Can create a video with the same file extension mp4........However, it can utilize different codecs that are compatible with Camtasia.
A program like Handbrake or VLC media player. Will usually convert the video so that it becomes compatible with Camtasia using default settings.
Handbrake is one of the better converters and it’s free, but not that intuitive. https://handbrake.fr/
Here’s a video with basic instructions.
VLC Media player is another free option. https://www.videolan.org/vlc/
If it were me, I would use Handbrake. I'm not sure how well VLC works. It's just another option to consider.