You cannot embed Transana clips in PowerPoint because Transana does not edit the raw video but instead loads the full video and positions it according to the stored Clip data.
We recommend running Transana and PowerPoint simultaneously, with Transana in Presentation Mode and all the Clips stored in a custom Collection. You can use the "Alt-Tab" key combination on Windows to switch between your presentation and the display of your Clips within Transana. While it takes a little bit of practice to get used to this, the end result is worth it, and this process is usually much easier than custom-editing video for a presentation.