Overscan is a disgusting phenomenon that is tolerated as part of the NTSC television standard, and which victimizes U.S. owners of analog CRT television sets. Basically, all U.S. analog sets are adjusted so that between 5% and 20% of each edge of the broadcast picture is discarded in the interest of having a larger percentage of manufactured CRT's pass minimum picture quality requirements.
Overscan is the cause of the mysterious disappearance of the subtitles when you transcode P2P files to NTSC dvd. The subtitles have not disappeared, they have fallen victim to overscan. Some dvd players, but as time passes fewer and fewer of them, offer a 0.8 incremental zoom factor specifically for the purpose of handling overscan.
Use of the Transcode option -j -18,-34,-22,-34 will undo the effect of overscan on nearly all analog televisions.
If the source material is 16:9 or greater letterboxed into 4:3, the option should be changed to: -j -8,-34,-8,-34.
Furthermore, if the export aspect ratio is 16:9, you will need to use -j -16,-36,-16,-36 because, SURPRISE, wide screen digital TV's in the U.S. also have overscan!!
This page explains overscan with examples: http://www.mastersofcinema.org/reviews/03lookingbeyond.htm
(Thanks to Trond Trondsen and Jan Bielawski for permission to link to their site!)