Many years ago I wrote a PIC program to count frame outputs from the LM1881 connected to reference output on a Sony VTR and also read and decode the RS422 deck control between the VTR and an Avid. This was needed because sometimes the Sony digibeta cameras would not lace up correctly to the last frame from standby and skip one or two frames in timecode. The Avid would not detect anything less than 6 frames as a timecode break and just keep recording. Editors were finding the ingested material could progressively loose lip-sync the more start/stops there were on the tape that Avid failed to detect. The PIC could detect single frame drops and then force the Avid to detect the dropout and then start the mark, pre-roll & record just beyond the break.
I just wondered if using the LM1881 you could easily detect when video is present/missing and then maybe use something like http://arduino.cc/playground/Main/TVout to keep the signal alive (so the TV does not turn off after a short time?). As there is no signal (when it's lost) then there should be no need to worry about correct colour and audio sub carriers, just create your own monochrome with correct porches and syncs as I assume the linked program does.