well its a TV tuner, so of course its going to have a coax input. Although you'll need to make sure your source can set the video to work on channel 3 or 4, like a regular tv.

All HDD home recorders can, like Richard already wrote, playback footage while recording that same footage. So, just start playback 5 minutes after you started recording and you are set. A 160GB unit costs less than $500 and will allow good quality delayed video for several tens of hours before the HDD get full.

I know there are tons of options but the main problem is finding a device that has a coaxial input which does not require to be tuned to a certain channel, since the XL2 can not output to a certain channel.

I need something that has a coaxial connection that treats it as a plain ole signal.

Put an VCR in between. XL2>VCR (short video cable), VCR (antenna out)> long coax> DVD recorder antenna in.

That would probably work, but is there anything simpler/smaller than a vcr that will acomplish this?

This may be a little late to be of help but I saw this thread last month and then the other day I stumbled across the sony dsr-1000. It will allows playback of any segment while still recording. Good luck, Jason.