If you follow news of the Web for a while, you can't help but notice that when a site really takes off, others will borrow the model and repurpose it to their own agenda. There are now dozens of Digg clones and an open-source CMS (Pligg) that'll let anyone host his own Digg-like site. People are making Digg-like sites for all kinds of specialized interests. One of my favorites is BioWizard- a sort of Digg for biomedical literature.
Youtube is another site that others are borrowing the model of. The model-borrowing has been going on for a while now, but is really getting interesting lately. Two variations on YouTube have recently come to my attention, PornoTube and JesusClips. (I'm not posting a link to either one of them- you can find them via Google if you like.) Talk about opposite ends of the spectrum.
I think that one of these two sites is potentially damaging to the human mind. If you know me, you'll know which one. Below, screen captures of YouTube, JesusClips, and PornoTube:
PornoTube (Image censored for those with delicate sensibilities)
Expect to see a lot more of these. There are already a couple of packages available that will let pretty much anyone with the bandwidth run a video-sharing site like YouTube. Expect an open-source version in the near future.
There are already at least three sites of this type for "adult" content. There will be dozens more soon.
Someone will try to make a site like this for kids, but will run into the problem of the need for strict editorial control in order to avoid showing kids content that parents would not approve of. That means that it'll have to be maintained by a corporate entity with the money to staff it properly. Betcha' it'll be Viacom.
All the "social networking" sites will soon all have native support for recording and posting video.
Comedy Central now posts clips from the Daily Show and Colbert Report in embeddable flash players. Expect most other networks to do the same.