I had asked in another thread about finalizing a DVD after burning, but my question was never address so I did some research on the subject. Thought this explanation might help someone else too:

(snip)

"Open Computer by clicking the Start button Picture of the Start button, and then clicking Computer. (I have a shortcut on my desktop)

In Windows Explorer, click the disc burner drive, and then click Close session on the toolbar.

The session will be closed, so the disc can be used in other computers.

Notes

After you close a disc session for multi-session capable discs, you can still add more files to the disc, but you must close each additional session to be able to use the disc on another computer. About 20 megabytes (MB) of disc space is used each time you close a session.

If you remove a disc from your burner without closing the disc session, you can close it later on. Just insert it back into your computer's disc burner and follow the steps above to close the session.

Some programs might finalize your disc instead of closing the current session. You can't add any additional files to a disc that has been finalized. When you burn a CD or DVD using Windows Explorer, the disc is not finalized."

(end)

I would assume it would work the same in W8 too......?

Link: http://windows.microsoft.com/en-us/windows/close-finalize-cd-dvd#1TC=windows-7