Advice for DVD commentators

It seems every movie on DVD today has to have some kind of audio commentary on it, as if it was a requirement. Some of these commentaries are quite enlightening, while others are just plain boring as hell.

So here's some advice for commentators:

1. If it's something you haven't seen in years, watch it once before going to the recording session. It's not a lot to ask. Maybe it will kill a little bit of the spontaneity, but that's so much more preferable to minutes of silence punctuated by the commentator saying something like "It's been so long since I've watched this, I didn't even remember that scene."
2. It's OK to laugh at your own jokes. But don't assume the viewer hasn't heard the joke before, so don't be afraid to retell the joke in your own words, or laugh before the punchline is uttered on the principal audio track. No one I know first watches with the commentary on and then goes back to watch again without the commentary. And if they do that, they've already seen the film in the theater or the show on TV.
3. Enunciate! Your witty commentary is useless if no one can understand what you're saying. Some DVDs have subtitles for the commentary track, but you'd do well to assume that your DVD won't.
3a. But if English isn't your native language, you should still try to do an audio commentary, and not go for a text commentary. You can probably spell better than any native speaker, but do you have any idea how distracting it is to read subtitles that don't match up with the audio track?
4. A commentary is not the place the vent about your frustrations with specific individual actors, directors, writers. Especially if you plan to work with them again in the future. It's another thing to complain about censors, or even to bite the hand that feeds you. But to badmouth your equals and your subordinates is just plain unprofessional.