As part of their massive pre-release FAQ for the PlayStation 4, Sony revealed that the console will not allow direct uploads to YouTube at launch.
Can I share my game videos on YouTube?

No. At launch, PS4 users will be able to use the Share button on the DUALSHOCK 4 controller to upload gameplay videos to their Facebook account, or to stream live gameplay to Ustream or Twitch. PS4 owners can follow PlayStation.Blog and PlayStation.com for further news on other services to come after launch.

Right now, the streams sent to Twitch will be archived for later viewing if the user has archiving enabled on their account ahead of time. As noted in the FAQ, there are other solutions coming after launch which will be revealed later.

They also note that recorded gameplay video will not be able to be directly copied to other devices from the PS4. This does not really answer the question as to whether or not a capture device will be a viable alternative.