The Habit of Regular Videos
Build a Following
Keep Your Students in the Loop
Equipment for Professional Videos
For most educational purposes, the camera and microphoneon your smartphone is likely good enough. I've done conference livestream videos with an iPhone 5s, and they didn't turn out terribly. However, if you plan on doing regular videos, you may consider borrowing or purchasing better equipment to provide a somewhat better experience for your viewers.
I also recommend the article by Stephen R. Crawford on Making a First Impression with Introduction Videos. He also addresses many of the technical requirements for a effective videos.
Image Stability: Tripod or Webcam
In terms of video quality, the one absolute necessity is a stable image. You aren't filming The Blair Witch Project or Cloverfield. You aren't aiming for those intense, gut-wrenching scenes from Battlestar Galactica. Instead, you're trying to convey information.
This is the one place where webcams carry a major advantage: whether integrated as part of your computer or made to sit on a tabletop, they are designed to remain in a fixed position. Smartphones and professional video cameras are instead designed to be held — you will need to stabilize them if you use them for video blogging.
Video Quality: HD or Better
Today's audiences expect HD-quality video. As internet speeds continue to improve, 4K may or may not become the minimum standard. For the purposes of video blogging, SD-quality simply won't cut it today, so many webcams and front-facing smartphone cameras may fall short. But that's okay — your smartphone almost certainly has an HD camera for the rear-facing camera, and it will most likely work fine. Some also have an HD-quality front-facing camera, and that makes it easier to see yourself and ensure proper positioning as you film your video.
However, I recommend using the highest quality camera you have available. And make sure the lens is clear — no digital tool can erase the halos created by smudges on the lens.
Sound Quality: External Microphones Are Almost Essential
If you plan on producing regular videos, you need decent sound. Increasingly, smartphones use multiple microphones to cancel extraneous noise and provide clear sound, and it's possible your smartphone produces decent sound for video blogging. Most, however, do not. Most likely, you'll need an external microphone to provide the crisp, clear voice that audiences expect. And I don't mean the pinhole mic from your earbuds — a useful external microphone will be relatively large, it will have either foam or a metal grill to shield the mic from wind and breathing, and it will likely require either USB or a dedicated microphone port. Most phones don't have these easily available — here, computers and camcorders have the advantage, though adapters are available for many smartphones.