Any way to seek in a growing file?

[scgroup]

I would like to be able seek within a remote TV program that has not yet completed, e.g. begin watching basketball an hour after the game starts, and be able to skip over commercials and halftime, as well as back up to replay missed action.

The system presently consists of: Video source->Slingbox->LAN->Recorder app->file->FTP server->Internet->FTP client->file->VLC. The "FTP" client and server are actually custom apps that throttle the transfer when near the end, so as not to overrun the file written by the recorder. The files are presently in native Slingbox format (H.264 + AAC, ASF container).

Currently, one can begin watching e.g. a minute after the program starts, but cannot seek or skip. Also, if network congestion or another technical issue delays the transfer, VLC quits and must be restarted from the beginning. Alternatively, one can wait for the program to end, index the file, and have full seek capability.

So, I'm looking for a way to make VLC seek without an index (approximate would be fine, e.g. skip forward 15 MB), or have it use a growing index (which I'd modify the app to create). Ideally, if it reached the current end of the file, I'd like it to wait for more data and continue playing, but stopping would be ok, too, if it weren't hard to get it started again.

If needed, I'd consider re-containering the file (I don't have enough horsepower to recode it in real time), using a different OS, etc. A different player or other component would be fine, too.

Thanks in advance for your guidance.