Which specific model of DVD recorder do you have? You need to finalize the disc on the unit that wrote the files/movie to disc. For the Toshiba DR570KU, press Setup on the remote. Then enter the DVD menu (use the up/down arrows to navigate and then press Enter). Select Finalize and then press Enter. Highlight Yes when asked to confirm the finalization step and then press Enter again. Wait for the recorder to finish the process (it will take several minutes). Note: you need to leave some space on the disc for the finalization data to be added to it.
You can also set the unit to auto-finalize when the disc is full or a timed recording ends. For the second item, you will not be able to add content to the disc if a short program was recorded unless you use a rewritable DVD. (Then you would will need to unfinalize the disc. See the manual.) This is accessed from the General Settings menu from the Setup button. Go to Recordings and then select the Auto Finalize setting. Select when you want the disc to finalize and then turn ON the feature. Press Setup to exit the menu.
The manual for the DR570 is available under the User's Guide tab here: http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/modelContent.jsp?ct=SB&os=&category=&moid=2805105&rpn=undefined&modelFilter=DR570KU&selCategory=2797338&selFamily=2797342
. Toshiba has the manuals to most of their products here: http://www.csd.toshiba.com/cgi-bin/tais/support/jsp/home.jsp
Please add a comment with the specifics of your recorder for more information. I hope this helps.