Adding a Director Track

Digitizing the footage and do a voice over using the tool in FCP.

Then, encode to DVD with two tracks, one with the original sound and the voice over, and the other with just the original sound.

Do two angles for the audio track in DVD SP.

If you want to allow someone to hear either the original sound or the narrative, then DVD seems to be the only option.

You also can digitize the footage into iMovie, and then use a USB Microphone to record a separate sound track in iMovie perhaps.

But only DVD SP can create angles, iDVD cannot. So you need two DVDs.

But there is no way to my knowledge to create a way for a video tape to play different soundtracks

This is a finalcutpro forum.

Ooooo. Thank goodness Michael is policing this site. We can't let things get out of hand, can we?

Phew!

That was a close one.

Thanks Mike.

H.

Anytime.

to be fair the OP was complaining that the advice given required him to have fcp/dvdsp. Michael was just pointing out that on this forum most solutions are going to involve fcp.

excuse me, but just a few posts ago you said:
"So I need final Cut Pro and DVD Studio Pro. Both I do not have... is that my only option?"

If you have fcp5 and dvdsp, you will be able to do what you asked.

'Old' is relative. There's nothing wrong with either of these versions, and they're still more suited to the task than the latest versions of imovie or dvd.
So, as has already been said;
Make a new sequence in FCP. Edit your original movie into it. Use VO tool to create your commentary. Do it in multiple sections/takes to make it easier to get right. Adjust the levels of the original audio so that it is at a low level when you're talking and higher where you want people to be able to hear the live sound. Once you're happy with it use 'export with compressor' to export the audio as .ac3 (2 tracks of aiff could cause your bitrate to be too high)

Then make a dvd project. Import your original movie and then import your new commentary track and drop it onto the second audio track. Create your menus and include a button ('play with commentary' perhaps) that has the second audio track selected as a target.