I’ve followed the steps below and it worked for me. I’d suggest you edit/join the video files on IMovie for example and then you would have similar video files.
basically the steps show you how to uninstall and reinstall Roxio.
As a suggestion, Please try to clean uninstall and reinstall Toast 18. Quit Toast, trash the entire Toast 18 folder (located in Finder > Applications), then do the same for any previous versions of Toast, if you still have any installed. You need to remove all previous versions of Toast to avoid possible conflicts. Next is to check for the files listed below. If you see any of them, trash them: "Roxio Toast Prefs" “com.roxio.ScreenCapture.plist” "com.roxio.toast.plist" "com.roxio.Toast.LSSharedFileList.plist" "com.roxio.MyDVD.plist" "com.roxio.videoplayer.plist" “com.roxio.videoplayer.LSSharedFileList.plist” “com.corel.Toast-Audio-Assistant.plist” You should be able to locate these files in ~/Library/Preferences. On the taskbar at the top, click on "Go", and select "Go To Folder...". Type in "~/Library/Preferences", without the quotes. Locate the above files in the Preferences folder that comes up and delete them. You must use this procedure because this particular Library folder is hidden from view, and this is how to open hidden folders. Aside from deleting the plist and Prefs files under the hidden Library/Preferences folder, you also need to delete other files/folders from these locations: Hidden Library sub-folders: -Preferences > plist and Prefs files -Application support > Roxio folder -Caches > Com.roxio.toast -Saved application state > com.corel.toastxxx.savedstate, com.roxio.toastxxx.savedstate -Services > Toastit.service Shortcut to bringing up the hidden Library folder (so you don’t need to use the Go To Folder search tool) is to open a Finder window, press and hold down the “Option” key on the Mac keyboard, then click Go > Library on the taskbar at the top of the screen. Notice that if you release the “Option” key, the “Library” item on the Go menu disappears. Pressing the Option key again makes the Library item re-appear. Once the procedure is complete, reboot your Mac, then reinstall your Toast 18. http://softwareupdates.roxio.com/downloads/toast/18/Toast_18.dmg