Personal Film Commentaries: The Next Trend?

I've long been a fan of filmmaker commentary tracks. It's the first thing I look for when scanning the back of a DVD case for special features. I don't consider a DVD presentation to be complete without a commentary track; and in the occasional case of multiple commentaries for a single film -- usually following the pattern of one with the director, producer or writer (the "technical" commentary) and one with the cast (the "fun" commentary) -- well, that's all the better.

My interest, then, was more than piqued by the recent commercial advertisements for The Dark Knight on Blu-Ray which heavily promotes its feature of enabling Blu-Ray-enabled PC users to create their own commentary track -- whether for a single favorite scene or the entire film -- using their webcam and microphone, and share it with others.

The idea of creating custom, "non-official" commentaries is hardly new. What movie nerd hasn't, at least in passing, had the idea of giving their favorite film the proper commentary justice? Harry Potter fans have been especially enthusiastic about creating their own commentary tracks for others to download (a good sampling here). The creators of Mystery Science Theater created Riff Trax, a site featuring humorous commentary tracks to popular movies that users can download for a small purchase fee.

The only minor problem with these "outside" commentaries is that they play separately from their respective DVD and must be synched properly in order to make sense. The Dark Knight is, as far as I know, the first movie to embrace fan-created commentaries. It seems so natural to give film buffs the opportunity to show off their knowledge of a particular film, that it's a wonder no one thought of it until now.

Is this just a clever marketing scheme? A fad? Or is this the next trend in home movie production? As technology and studio support eases the creation and sharing of personal commentaries, could they become standard? Would directors and actors take the time to sit down and record commentaries, or just let the devoted fans handle it?