Is there a way of telling 'get_iplayer' to terminate the download if it fails to download a segment?

Thanks,
Neil

Not really. You can specify a single recording mode so get_iplayer won't fall back to lower quality streams if the initial download fails. You can also use --attempts=1 to minimise the retries for each stream (default is 3).

--download-abortonfail option added in v3.09